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| author | link <link@localhost> | 2003-05-24 20:32:50 +0000 |
|---|---|---|
| committer | link <link@localhost> | 2003-05-24 20:32:50 +0000 |
| commit | ad55505ac9e7be6346dc97f3f0f0082e9b4e88be (patch) | |
| tree | c5d3f870a93a3ad458a7fd9d91b82a27291cc188 /htdocs/docs/errors.html | |
| parent | b6cb0baa3d77fad45374094a80c23629e59934a3 (diff) | |
| download | markup-validator-ad55505ac9e7be6346dc97f3f0f0082e9b4e88be.zip markup-validator-ad55505ac9e7be6346dc97f3f0f0082e9b4e88be.tar.gz markup-validator-ad55505ac9e7be6346dc97f3f0f0082e9b4e88be.tar.bz2 | |
Merging from validator-0_6_0-branch, at tag validator-0_6_2-beta1, to HEAD.
Diffstat (limited to 'htdocs/docs/errors.html')
| -rwxr-xr-x | htdocs/docs/errors.html | 1377 |
1 files changed, 612 insertions, 765 deletions
diff --git a/htdocs/docs/errors.html b/htdocs/docs/errors.html index 00b751c..b819f13 100755 --- a/htdocs/docs/errors.html +++ b/htdocs/docs/errors.html @@ -1,5 +1,5 @@ -<!--#set var="revision" value="\$Id: errors.html,v 1.25 2003-02-24 23:33:19 ville Exp $" ---><!--#set var="date" value="\$Date: 2003-02-24 23:33:19 $" +<!--#set var="revision" value="\$Id: errors.html,v 1.26 2003-05-24 20:32:46 link Exp $" +--><!--#set var="date" value="\$Date: 2003-05-24 20:32:46 $" --><!--#set var="title" value="Error Explanations for The W3C Markup Validation Service" --><!--#set var="relroot" value="../" --><!--#include virtual="../header.html" --> @@ -9,770 +9,617 @@ and are used here with his permission. </p> -<div id="toc"> -<h2 id="TableOfContents">Table of Contents</h2> -<ul> - -<li><a href="#undef-id"> -“ID ‘<var>FOO</var>’ already defined” -</a></li> - -<li><a href="#unterm-comment-1"> -“entity end not allowed in comment” -</a></li> - -<li><a href="#unterm-comment-2"> -“name start character invalid: only s and comment allowed in comment declaration” -</a></li> - -<li><a href="#bad-comment"> -“unknown declaration type ‘<var>FOO</var>’” -</a></li> - -<li><a href="#attr-quoted"> -“an attribute value must be a literal unless it contains only name characters” -</a></li> - -<li><a href="#attr-char"> -“character `X' not allowed in attribute specification list” -</a></li> - -<li><a href="#name-length"> -“length of attribute value must not exceed LITLEN less NORMSEP (1022)” -</a></li> - -<li><a href="#undef-tag"> -“element ‘<var>FOO</var>’ undefined” -</a></li> - -<li><a href="#not-allowed"> -“document type does not allow element ‘<var>FOO</var>’ here” -</a></li> - -<li><a href="#not-contained"> -“document type does not allow element ‘<var>FOO</var>’ here; assuming missing ‘<var>BAR</var>’ start-tag” -</a></li> - -<li><a href="#attr-undef"> -“there is no attribute ‘<var>FOO</var>’ for this element (in this HTML version)” -</a></li> - -<li><a href="#undef-attr-val"> -“‘<var>FOO</var>’ is not a member of the group specified in the declared value of this attribute” -</a></li> - -<li><a href="#bad-attr-char"> -“syntax of attribute value does not conform to declared value” -</a></li> - -<li><a href="#attr-bad-name"> -“value of attribute ‘<var>FOO</var>’ invalid: "#" cannot start a name” -</a></li> - -<li><a href="#bad-abbrev-attr"> -“‘<var>FOO</var>’ is not a member of a group specified for any attribute” -</a></li> - -<li><a href="#attr-missing"> -“required attribute ‘<var>FOO</var>’ not specified” -</a></li> - -<li><a href="#no-end-tag"> -“end tag for ‘<var>FOO</var>’ omitted, but its declaration does not permit this” -</a></li> - -<li><a href="#floating-close"> -“end tag for element ‘<var>FOO</var>’ which is not open” -</a></li> - -<li><a href="#omitted-content"> -“end tag for ‘<var>FOO</var>’ which is not finished” -</a></li> - -<li><a href="#no-start-tag"> -“start tag for ‘<var>FOO</var>’ omitted, but its declaration does not permit this” -</a></li> - -<li><a href="#bad-entity"> -“unknown entity ‘<var>FOO</var>’” -</a></li> - -<li><a href="#bad-char"> -“non SGML character number ###” -</a></li> - -<li><a href="#unicode-char"> -“`####' is not a valid character number” -</a></li> - -<li><a href="#bad-pub-id"> -“cannot generate system identifier for entity `HTML'” -</a></li> - -<li><a href="#missing-subel"> -“missing a required sub-element of ‘<var>FOO</var>’” -</a></li> - -<li><a href="#start-tag"> -“start tag was here” -</a></li> - -<li><a href="#utf8-bom"> -“UTF-8 'BOM' detected and removed” -</a></li> - -<li><a href="#text-not-allowed"> -“ text is not allowed here; try wrapping the text in a more descriptive container” -</a></li> - -<li><a href="#unkn-att-val"> -“ value of attribute ‘<var>FOO</var>’ cannot be ‘<var>BAR</var>’; must be one of ‘<var>FOO</var>’, ‘<var>BAR</var>’, ‘<var>BAZ</var>’” -</a></li> - -<li><a href="#no-attr-end"> -“character ‘<var>FOO</var>’ not allowed in attribute specification list possibly caused by a missing quotation mark ending a previous attribute value” -</a></li> - -<li><a href="#dup-attr"> -“duplicate specification of attribute ‘<var>FOO</var>’” -</a></li> - -<li><a href="#invalid-attr-val"> -“invalid attribute value” -</a></li> - -<li><a href="#attr-spec-nmtoken"> -“an attribute specification must start with a name or name token” -</a></li> - -<li><a href="#inval-comment"> -“invalid comment declaration; check your comment syntax” -</a></li> - -<li><a href="#assuming-missing-starttag"> -“element ‘<var>FOO</var>’ not allowed here; assuming missing ‘<var>BAR</var>’ start-tag”</a> -</li> -</ul> -</div> - - -<h2>Listing of errors and their explanation</h2> - - <dl> - <dt><a id="undef-id" name="dup-id">“<code>ID ‘<var>FOO</var>’ already defined</code>”</a></dt> - <dd> - <p> - You have defined the id/name ‘<var>FOO</var>’ more then once. You will also get - a message telling you where it was first defined. Be aware that this - message may be the result of an ambiguity in the specification. - While user-agents must treat values of the id attribute - as case-sensitive, they must still be case-insensitive unique in the - document. See - <a href="http://www.w3.org/TR/html4/struct/links.html#h-12.2.1">Section - 12.2.1 Syntax of anchor names</a> in the HTML 4.01 Recommendation - for further information. - </p> - </dd> - <dt><a id="unterm-comment-1" name="unterm-comment-1">“<code>entity end not allowed in comment</code>”</a></dt> - <dd> - <p> - Unterminated comment. The position indicator points to the very end of - the file, where the problem was detected; to find the beginning of the - comment, try searching for the last occurrence of - `<code><!--</code>' in the document. - </p> - </dd> - <dt><a id="unterm-comment-2" name="unterm-comment-2">“<code>name start character invalid: only s and comment allowed in comment declaration</code>”</a></dt> - <dd> - <p> - Unterminated comments again. This time, you have a case like: - </p> - <pre> - <!-- This is the first unterminated comment > - <!-- This is the second one > - </pre> - <p> - The validator (correctly) interprets the `<code>--</code>' in the - second comment as terminating the first comment, and then interprets - the text of the second comment as text between comments, which is not - allowed. - </p> - </dd> - <dt><a id="bad-comment" name="bad-comment">“<code>unknown declaration type ‘<var>FOO</var>’</code>”</a></dt> - <dd> - <p> - Most likely an invalid comment of the form <code><!invalid - comment></code>; the validator is (correctly) attempting to - interpret it as an <a href="sgml.html#sgml">SGML</a> markup - declaration. - </p> - </dd> - <dt><a id="attr-quoted" name="attr-quoted">“<code>an attribute value must be a literal unless it contains only name characters</code>”</a></dt> - <dd> - <p> - You have an attribute whose value needs to be in quotes. If an - attribute value contains any character other than letters, digits, - hyphens and periods, it must be enclosed in double quotes (single - quotes would also be OK from an <a href="sgml.html#sgml">SGML</a> - standpoint, but some browsers don't recognize them). - </p> - </dd> - <dt><a id="attr-char" name="attr-char">“<code>character `X' not allowed in attribute specification list</code>”</a></dt> - <dd> - <p> - The validator has found a character inside an HTML tag that isn't - allowed there. This usually means you didn't put an attribute value in - quotes when necessary. It also probably means that the character in - question is not allowed in the value of the attribute at all, or you - would have received the <a href="#attr-quoted">previous error</a> - instead. See <a href="#bad-attr-char">below</a> for more information. - </p> - <p> - You can also get in trouble by forgetting the closing quote on an - attribute. For instance: - </p> - <pre> - <IMG SRC="http://foo.com/fred.gif> - <IMG SRC="http://foo.com/joe.gif> - </pre> - <p> - The validator will (correctly) interpret this as a SRC value of - <code>"http://foo.com/fred.gif> <IMG SRC="</code>, and then - choke on the following `:'. In this case, the position indicator in - the error message may be several lines below the line with the missing - quote. - </p> - </dd> - <dt><a id="name-length" name="name-length">“<code>length of attribute value must not exceed LITLEN less NORMSEP (1022)</code>”</a></dt> - <dd> - <p> - This usually occurs in conjunction with the - <a href="#attr-char">previous error</a>. It almost always means that - you've forgotten a closing quote on an attribute value. For instance, - in: - </p> - <pre> - <IMG SRC="fred.gif> - <!-- 50 lines of stuff --> - <IMG SRC="joe.gif"> - </pre> - <p> - The SRC value for the first <code><IMG></code> is the entire - fifty lines of stuff up to the next double quote, which probably - exceeds the <a href="sgml.html#sgml">SGML</a>-defined length limit for - HTML string literals. Note that the position indicator in the error - message points to where the attribute value <em>ended</em> — in - this case, the <code>"joe.gif"</code> line. - </p> - </dd> - <dt><a id="undef-tag" name="undef-tag">“<code>element ‘<var>FOO</var>’ undefined</code>”</a></dt> - <dd> - <p> - You've used an unknown tag (represented here by ‘<var>FOO</var>’). Make sure the - DTD indicated by your DOCTYPE actually includes this element. - </p> - <p> - If the tag in question is a frame-related tag you must use the - "Frameset" DTD, and if you use (deprecated) physical markup ("FONT" - and friends) you must use the "Transitional" DTD. - </p> - </dd> - <dt><a id="not-allowed" name="not-allowed">“<code>document type does not allow element ‘<var>FOO</var>’ here</code>”</a></dt> - <dd> - <p> - Straightforward, but not terribly informative. There are a - <em>lot</em> of different errors that will generate this error - message: - </p> - <ul> - <li> - Using an unknown tag. In this case, the next error will be - <a href="#undef-tag">“element ‘<var>FOO</var>’ undefined"</a>. - </li> - <li> - Using a tag in the wrong place. For instance, - <code><TABLE><TD>blah</TABLE></code> will cause - this error. The trick here is that <code><TABLE></code> cannot - <em>directly</em> contain <code><TD></code>'s; it contains - <code><TR></code>'s which contain <code><TD></code>'s. - The above example should be - <code><TABLE><TR><TD>blah</TABLE></code>. - </li> - </ul> - </dd> - <dt><a id="not-contained" name="not-contained">“document type does not allow element ‘<var>FOO</var>’ here; assuming missing ‘<var>BAR</var>’ start-tag</a>’</dt> - <dd> - <p> - Similar to the <a href="#not-allowed">previous error</a>, but more - specific: in this case, you have a ‘<var>FOO</var>’ element that is not contained - in a ‘<var>BAR</var>’ element when ‘<var>FOO</var>’ is not allowed outside of ‘<var>BAR</var>’. Some of the - most common causes of this error are: - </p> - <ul> - <li> - Using the <code>DD</code> element as a fake paragraph indent. - <code>DD</code> is not allowed outside of a <code>DL</code> element. - </li> - <li> - Improper construction of a nested list. An inner UL or OL in a - nested list may not appear directly within an outer UL/OL, but only - within an LI of the outer UL/OL, as in the following example: - <pre> - <OL> - <LI>Obtain the following items: - <UL> - <LI>Ham</LI> - <LI>Bread; one of: - <UL> - <LI>White</LI> - <LI>Rye</LI> - <LI>Whole wheat</LI> - </UL> - </LI> <!-- End of the "Bread" <LI> --> - <LI>Cheese</LI> - </UL> - </LI> <!-- End of the "Obtain" <LI> --> - <LI>Place ham and cheese between two slices of bread</LI> - <LI>Consume the resulting ham-and-cheese sandwich</LI> - </OL> - </pre> - <p> - The <code></LI></code> end tags are optional and are only - included above to emphasize how the structure of the nested list - is arranged; if you omit them, the parser will infer their - presence in the locations shown above. - </p> - </li> - </ul> - <p> - The validator has inserted a ‘<var>BAR</var>’ start tag where it thinks there needs - to be one; it will probably complain later on that <a href="#no-end-tag">the - corresponding end tag is also missing</a>. - </p> - </dd> - <dt><a id="attr-undef" name="attr-undef">“<code>there is no attribute ‘<var>FOO</var>’ for this element (in this HTML version)</code>”</a></dt> - <dd> - <p> - You have used an attribute with an element that is defined not to have - that attribute. This is most commonly caused by using - vendor-specific attributes without setting the document type - appropriately. - </p> - </dd> - <dt><a id="undef-attr-val" name="undef-attr-val">“<code>‘<var>FOO</var>’ is not a member of the group specified in the declared value of this attribute</code>”</a></dt> - <dd> - <p> - Similar to the <a href="#attr-undef">previous error</a>; this time, - you're using an attribute that is defined for the element, but with a - value that isn't defined for the attribute. For instance, the Netscape - extension <code><IMG ALIGN=ABSMIDDLE></code> will cause this - error; ABSMIDDLE isn't one of the allowed values for the ALIGN - attribute of <code><IMG></code> (unless, of course, you provided - a Netscape document type). - </p> - <p> - If you're using the Netscape document type, the BORDER attribute of - <code><TABLE></code> can cause this error. - </p> - <p> - This error can also be caused, oddly enough, by missing close quotes - on attribute values. For instance, given: - </p> - <pre> - <IMG SRC="fred.gif> <IMG SRC="joe.gif> - </pre> - <p> - The validator will (correctly) see a SRC attribute of - <code>"fred.gif> <IMG SRC="</code>, and then try to interpret - JOE.GIF as an attribute of <code><IMG></code>. - </p> - </dd> - <dt><a id="bad-attr-char" name="bad-attr-char">“<code>syntax of attribute value does not conform to declared value</code>”</a></dt> - <dd> - <p> - Yet another attribute error; this time, the attribute in question was - defined to take a numeric value, or an <a - href="sgml.html#sgml">SGML</a> identifier value, and you used a - character that doesn't match what it was expecting. - </p> - <p> - One potentially annoying source of this error is the <code>TD - WIDTH</code> attribute. Whether intentionally or by oversight, the - HTML 3.2 DTD defines this attribute to have a value type of NUMBER, - which means that <code><TD WIDTH="50%"></code> is not allowed. - </p> - </dd> - <dt><a id="attr-bad-name" name="attr-bad-name">“<code>value of attribute ‘<var>FOO</var>’ invalid: "#" cannot start a name</code>”</a></dt> - <dd> - <p> - A special case of <a href="#bad-attr-char">the previous error</a>; the - attribute in question is defined to take as value an SGML name token, - which must begin with a letter. - </p> - </dd> - <dt><a id="bad-abbrev-attr" name="bad-abbrev-attr">“<code>‘<var>FOO</var>’ is not a member of a group specified for any attribute</code>”</a></dt> - <dd> - <p> - Another attribute error, this time referring to an "abbreviated" - attribute. <a href="sgml.html#sgml">SGML</a> allows you to omit the - name of an attribute if the attribute value is unambiguous. For - instance, <code><IMG ISMAP></code> is actually an abbreviation - of <code><IMG ISMAP=ISMAP></code>. (Technically, this also means - that e.g. <code><P ALIGN=CENTER></code> could be abbreviated to - <code><P CENTER></code>, but it is unlikely that current - browsers will get this right.) The validator has found something that - looks like an abbreviated attribute but doesn't match the value of any - attribute for this element. For instance, a typo like <code><IMG - ISNAP></code> would produce this error. - </p> - <p> - A missing close quote on a previous attribute value can also trigger - this error if the next quote it finds is followed by something that - looks like an abbreviated attribute; for instance, <code><IMG - SRC="fred.gif><IMG SRC="joe.gif></code> would produce this - error, referring to the "attribute value" <code>JOE.GIF</code>. - </p> - </dd> - <dt><a id="attr-missing" name="attr-missing">“<code>required attribute ‘<var>FOO</var>’ not specified</code>”</a></dt> - <dd> - <p> - You left off a required attribute of the indicated element. The most - common such omitted attribute is the <code>ALT</code> attribute of the - <code>AREA</code> or <code>IMG</code> element; browsers will typically - use these to build a menu equivalent to your client-side image map if - the user has disabled image loading, so you'll want to use a - meaningful value here. - </p> - </dd> - <dt><a id="no-end-tag" name="no-end-tag">“<code>end tag for ‘<var>FOO</var>’ omitted, but its declaration does not permit this</code>”</a></dt> - <dd> - <p> - You forgot to close something. ‘<var>FOO</var>’ is the element you forgot to close - (and the next message, `start tag was here' points to the particular - instance of ‘<var>FOO</var>’ in question); the positional indicator points to where - the validator expected you to close the element. There are a few - common ways that this can happen: - </p> - <ul> - <li> - You've put something inside the ‘<var>FOO</var>’ element that isn't allowed - there. For instance, <code><UL><LI><H4>fake font - change</H4></UL></code> will cause this error, since - headers aren't allowed inside <code><UL></code>'s; the - validator assumes that you meant to close the - <code><UL></code> before opening the <code><H4></code>. - </li> - <li> - Interlocked elements. For instance, - <code><B><I>nope</B></I></code> will cause - this error. HTML requires that you close elements “inside-out” - — that is, the last element you opened is the first element you should - close. In this example, you'd have to close the - <code><I></code> before the <code><B></code>. - </li> - <li> - Unclosed <code><A></code> tags. Yes, even <code><A - NAME="foo"></code> has to have a corresponding - <code></A></code>. Note that an empty <code><A - NAME></code> element won't be recognized by some browsers; be - sure to put at least a word or two inside the - <code><A></code>. - </li> - <li> - Having unadorned text where the validator was expecting a - sub-element of ‘<var>FOO</var>’. For instance, <code><DL>fake - indent</DL></code> will produce this error, since inside a - <code><DL></code>, the validator only expects to see - <code><DT></code>'s and <code><DD></code>'s. - </li> - <li> - A tag of the form <code><TABLE WIDTH=100%></code>. The - previous error should have been that the `%' was <a - href="#attr-char">"not allowed in attribute specification list"</a>. - What's happening here is that, in trying to get past the `%', the - validator has become confused and thinks the `%' is <em>inside</em> - the <code><TABLE>...</TABLE></code>, thus triggering the - error message for the previous reason. This error will likely be - followed by mistaken complaints that your <code><TR></code>'s - are <a href="#not-allowed">"not allowed here"</a>, plus a complaint - about your <code></TABLE></code> end tag. The solution is to - put the attribute value in quotes; ie. <code><TABLE - WIDTH="100%"></code>. - </li> - </ul> - <p> - In general, you should always explicitly close all elements and - quote all attribute values. - </p> - </dd> - <dt><a id="floating-close" name="floating-close">“<code>end tag for element ‘<var>FOO</var>’ which is not open</code>”</a></dt> - <dd> - <p> - The validator found an end tag, represented here by ‘<var>FOO</var>’, without a - corresponding start tag. This frequently occurs in conjunction with - the <a href="#no-end-tag">previous error</a>. For instance, given - <code><B><I>nope</B></I></code>, the validator - will insert a <code></I></code> before the - <code></B></code>, and then will find the - <code></I></code> after the <code></B></code> and will - have nothing to match it with. - </p> - <p> - A subtle variation of this is <code><P><H4>fake font - change</H4></P></code>. <code><H4></code>'s aren't - allowed inside <code><P></code>'s, but since HTML allows you to - omit the <code></P></code> end tag for paragraphs, the validator - assumes that you meant <code><P></P><H4>fake font - change</H4></P></code>, in which case the final - <code></P></code> is indeed superfluous. - </p> - <p> - This error can also be caused by incorrectly supplying an end tag for - "empty" elements like <code><HR></code>, <code><BR></code> - or <code><IMG></code>. - </p> - </dd> - <dt><a id="omitted-content" name="omitted-content">“<code>end tag for ‘<var>FOO</var>’ which is not finished</code>”</a></dt> - <dd> - <p> - You have a ‘<var>FOO</var>’ element, but you have omitted some required sub-element - of it. For instance, a <code>TABLE</code> with no <code>TR</code>'s - would cause this error. - </p> - </dd> - <dt><a id="no-start-tag" name="no-start-tag">“<code>start tag for ‘<var>FOO</var>’ omitted, but its declaration does not permit this</code>”</a></dt> - <dd> - <p> - The validator expected you to start a ‘<var>FOO</var>’ element at the indicated - point. This probably means you've put unadorned text somewhere it - isn't allowed; for instance, <code><UL>fake - indent</UL></code> will cause this error. - </p> - </dd> - <dt><a id="bad-entity" name="bad-entity">“<code>unknown entity ‘<var>FOO</var>’</code>”</a></dt> - <dd> - <p> - The validator has found an entity (something like - <code>&this;</code>) that it doesn't recognize. There are a few - possibilities: - </p> - <ul> - <li> - <p> - A reference to a URI that uses <code>&</code> as a separator - between parameters, such as - "<code>http://example.org/prog?x=1&y=2</code>". - </p> - <p> - To solve this problem, simply replace all the <code>&</code>'s - in attribute values with <code>&amp;</code> (user agents will - convert them back before following the links.) - </p> - <p> - Another way to get around this problem is for the author of the CGI - program to allow a different value to be used between arguments, - like ';' or '|', which would allow the link to be coded as e.g. - <code><a href="http://example.org/prog?x=1;y=2"></code> - </p> - </li> - <li> - An unterminated entity; for instance, <code>this&ampthat</code> - for "this&that", which the validator (correctly) interprets as a - request for the entity <code>&ampthat;</code>. Technically, any - non-alphanumeric character (such as a space) will suffice to - terminate the entity, but some browsers get this wrong; the safest - thing to do is to terminate all entities with a semicolon, turning - our example into <code>this&amp;that</code>. - </li> - <li> - The entity <code>&quot;</code> in conjunction with the HTML 3.2 - <code>DOCTYPE</code>. This entity was <a - href="http://lists.w3.org/Archives/Public/www-html/1997Mar/0003.html">accidentally - omitted</a> from the most recent version of the HTML 3.2 DTD. You - should be able to ignore this error safely, though if you wish, you - can replace <code>&quot;</code> with the equivalent character - entity <code>&#34;</code>. - </li> - </ul> - </dd> - <dt><a id="bad-char" name="bad-char">“<code>non SGML character number ###</code>”</a></dt> - <dd> - <p> - You've used an illegal character in your text. HTML uses the standard - ISO8859-1 character encoding, and ISO8859-1 leaves undefined 65 - character codes (0 to 31 inclusive and 127 to 159 inclusive); the - validator has found one of these undefined characters in your - document. The character may appear on your browser as a curly quote, - or a trademark symbol, or some other fancy glyph; on a different - computer, however, it will likely appear as a completely different - character, or nothing at all. - </p> - <p> - Your best bet is to replace the character with the nearest equivalent - ASCII character, or to use an appropriate <a - href="http://www.w3.org/hypertext/WWW/MarkUp/html3/latin1.html">character - entity</a>. For more information on ISO8859-1, see <a - href="http://ppewww.ph.gla.ac.uk/%7Eflavell/aflavell.html">Alan - Flavell</a>'s excellent <a - href="http://ppewww.ph.gla.ac.uk/%7Eflavell/iso8859/">ISO8859-1/HTML - reference</a>. - </p> - <p> - This error can also be triggered by formatting characters embedded in - documents by some word processors. If you use a word processor to edit - your HTML documents, be sure to use the "Save as ASCII" or similar - command to save the document without formatting information. - </p> - </dd> - <dt><a id="unicode-char" name="unicode-char">“<code>`####' is not a valid character number</code>”</a></dt> - <dd> - <p> - You'll get several occurrences of this error if you use the Cougar - DTD. Cougar uses the 16-bit UCS-4 (a.k.a. "Unicode") character set - instead of the 8-bit ISO8859-1 character set used by HTML 2.0 and HTML - 3.2. It also defines mnemonic entities for various Unicode characters; - for instance, the entity <code>&trade;</code> is defined as the - character entity <code>&#8482;</code>, which is the Unicode - trademark character. Unfortunately, the <code>nsgmls</code> executable - used by the validator does not appear to have 16-bit character support - compiled in, and so it chokes on these 16-bit character entities. - </p> - <p> - These errors are not produced by anything in your document and should - not otherwise affect the validation of your document, so you can - pretty much ignore them. - </p> - </dd> - <dt><a id="bad-pub-id" name="bad-pub-id">“<code>cannot generate system identifier for entity `HTML'</code>”</a></dt> - <dd> - <p> - Your <code>DOCTYPE</code> declaration contains a public identifier - that the validator doesn't recognize. See the <a - href="sgml.html#doctype">discussion of <code>DOCTYPE</code></a> for an - explanation of what's happening, and what public identifiers the - validator recognizes. - </p> - <p> - Note that all of the rest of the errors you received are meaningless; - the validator was unable to find a <a href="sgml.html#dtd">DTD</a> to - work from, and thus could not validate your document. - </p> - </dd> - <dt><a id="missing-subel" name="missing-subel">“<code>missing a required sub-element of ‘<var>FOO</var>’</code>”</a></dt> - <dd> - <p> - The element ‘<var>FOO</var>’ is defined to <em>require</em> one or more - sub-elements. One example is TR which requires one or more TD or TH - elements. - </p> - </dd> - <dt><a id="start-tag" name="start-tag">“<code>start tag was here</code>”</a></dt> - <dd> - <p> - Not an error, but rather a pointer to the start tag of the element - the previous error referred to. - </p> - </dd> - <dt><a id="utf8-bom" name="utf8-bom">“<code>UTF-8 'BOM' detected and removed</code>”</a></dt> - <dd> - <p> - The document contained an UTF-8 encoded Unicode Byte Order Mark (BOM) - as the first character and we have removed it before parsing. - Many XML Processors fail to recognize it (although it's perfectly - valid). To be on the safe side you may want to avoid using the - BOM in UTF-8 encoded documents until browsers are updated to support it. - </p> - <p> - Note that the BOM in <em>UTF-16</em> encoded documents - is required and handled by all conforming XML Processors. - </p> - </dd> - <dt><a id="text-not-allowed" name="text-not-allowed">“<code> text is not allowed here; try wrapping the text in a more descriptive container</code>”</a></dt> - <dd> - <p> - The document contained bare text where an element was expected. - For instance, you must wrap text in <code><p></code> if it - appears directly inside the <code><body></code>. - </p> - <p> - This error may also indicate an unquoted attribute value containing - a reserved character (such as "<samp>/</samp>") which terminates the - attribute. The net effect is that the rest of the attribute value - appears to be plain text, outside any element, to an SGML parser. - </p> - </dd> - <dt><a id="unkn-att-val" name="unkn-att-val">“<code> value of attribute ‘<var>FOO</var>’ cannot be ‘<var>BAR</var>’; must be one of ‘<var>FOO</var>’, ‘<var>BAR</var>’, ‘<var>BAZ</var>’</code>”</a></dt> - <dd> - <p> - An attribute was specified to contain one of a set of predefined - values and you have used a value that is not in that set. The error - message tells which attribute value was unknown and the possible - legal values for this attribute. - </p> - </dd> - <dt><a id="no-attr-end" name="no-attr-end">“<code>character ‘<var>FOO</var>’ not allowed in attribute specification list possibly caused by a missing quotation mark ending a previous attribute value</code>”</a></dt> - <dd> - <p> - A character that is illegal in the attribute list for a particular - attribute was encountered. It's is likely that this is a result of - a missing quote character on a previous attribute value. - </p> - </dd> - <dt><a id="dup-attr" name="dup-attr">“<code>duplicate specification of attribute ‘<var>FOO</var>’</code>”</a></dt> - <dd> - <p> - You have specified an attribute more than once. For instance, you've - used the "height" attribute on the "img" element twice on the same - "img" tag. - </p> - </dd> - <dt><a id="invalid-attr-val" name="invalid-attr-val">“<code>invalid attribute value</code>”</a></dt> - <dd> - <p> - The value of this attribute is not a legal value for attributes. For - instance, the attribute cannot be the empty string. This is distinct - from errors related to illegal values for a specific attribute. - </p> - </dd> - <dt><a id="attr-spec-nmtoken" name="attr-spec-nmtoken">“<code>an attribute specification must start with a name or name token</code>”</a></dt> - <dd> - <p> - An attribute name (and some attribute values) must start with one of - a restricted set of characters. This error usually indicates that - you have failed to add a closing quotation mark on a previous - attribute value (so the attribute value looks like the start of a - new attribute) or have used an attribute that is not defined - (usually a typo in a common attribute name). - </p> - </dd> - <dt><a id="inval-comment" name="inval-comment">“<code>invalid comment declaration; check your comment syntax</code>”</a></dt> - <dd> - <p> - There is a syntax error in an SGML Comment Declaration. This may be - caused by too many or too few hyphens "-" or that you have included - an invalid character in the comment. The next message will be - "comment declaration started here". - </p> - </dd> - <dt><a id="assuming-missing-starttag" name="assuming-missing-starttag">“<code>element ‘<var>FOO</var>’ not allowed here; assuming missing ‘<var>BAR</var>’ start-tag</code>”</a></dt> - <dd> - <p> - The referenced element ‘<var>FOO</var>’ isn't allowed in the context it occurs - in, but it would be if it was wrapped in a ‘<var>BAR</var>’ element. The - Validator has assumed that you have forgotten to add a ‘<var>BAR</var>’ - start tag and continued validation as if it was there. You should - check if this is the case and insert the proper tag. - </p> - </dd> -<!-- - <dt><a id="" name="">""</a></dt> - <dd> - <p> - </p> - </dd> ---> + <div id="toc"> + <h2 id="TableOfContents">Table of Contents</h2> + <ul> + <li><a href="#undef-id">ID "<var>FOO</var>" already defined</a></li> + <li><a href="#unterm-comment-1">entity end not allowed in comment</a></li> + <li><a href="#unterm-comment-2">name start character invalid: only s and comment allowed in comment declaration</a></li> + <li><a href="#bad-comment">unknown declaration type "<var>FOO</var>"</a></li> + <li><a href="#attr-quoted">an attribute value must be a literal unless it contains only name characters</a></li> + <li><a href="#attr-char">character `X' not allowed in attribute specification list</a></li> + <li><a href="#name-length">length of attribute value must not exceed LITLEN less NORMSEP (1022)</a></li> + <li><a href="#undef-tag">element "<var>FOO</var>" undefined</a></li> + <li><a href="#not-allowed">document type does not allow element "<var>FOO</var>" here</a></li> + <li><a href="#not-contained">document type does not allow element "<var>FOO</var>" here; assuming missing "<var>BAR</var>" start-tag</a></li> + <li><a href="#attr-undef">there is no attribute "<var>FOO</var>" for this element (in this HTML version)</a></li> + <li><a href="#undef-attr-val">"<var>FOO</var>" is not a member of the group specified in the declared value of this attribute</a></li> + <li><a href="#bad-attr-char">syntax of attribute value does not conform to declared value</a></li> + <li><a href="#attr-bad-name">value of attribute "<var>FOO</var>" invalid: "#" cannot start a name</a></li> + <li><a href="#bad-abbrev-attr">"<var>FOO</var>" is not a member of a group specified for any attribute</a></li> + <li><a href="#attr-missing">required attribute "<var>FOO</var>" not specified</a></li> + <li><a href="#no-end-tag">end tag for "<var>FOO</var>" omitted, but its declaration does not permit this</a></li> + <li><a href="#floating-close">end tag for element "<var>FOO</var>" which is not open</a></li> + <li><a href="#omitted-content">end tag for "<var>FOO</var>" which is not finished</a></li> + <li><a href="#no-start-tag">start tag for "<var>FOO</var>" omitted, but its declaration does not permit this</a></li> + <li><a href="#bad-entity">unknown entity "<var>FOO</var>"</a></li> + <li><a href="#bad-char">non SGML character number ###</a></li> + <li><a href="#bad-pub-id">cannot generate system identifier for entity `HTML'</a></li> + <li><a href="#missing-subel">missing a required sub-element of "<var>FOO</var>"</a></li> + <li><a href="#start-tag">start tag was here</a></li> + <li><a href="#text-not-allowed"> text is not allowed here; try wrapping the text in a more descriptive container</a></li> + <li><a href="#unkn-att-val"> value of attribute "<var>FOO</var>" cannot be "<var>BAR</var>"; must be one of "<var>FOO</var>", "<var>BAR</var>", "<var>BAZ</var>"</a></li> + <li><a href="#no-attr-end">character "<var>FOO</var>" not allowed in attribute specification list possibly caused by a missing quotation mark ending a previous attribute value</a></li> + <li><a href="#dup-attr">duplicate specification of attribute "<var>FOO</var>"</a></li> + <li><a href="#invalid-attr-val">invalid attribute value</a></li> + <li><a href="#attr-spec-nmtoken">an attribute specification must start with a name or name token</a></li> + <li><a href="#inval-comment">invalid comment declaration; check your comment syntax</a></li> + <li><a href="#assuming-missing-starttag">element "<var>FOO</var>" not allowed here; assuming missing "<var>BAR</var>" start-tag</a></li> + </ul> + </div> + + <div> + <h2>Listing of errors and their explanation</h2> + <dl> + <dt id="undef-id"><code>ID "<var>FOO</var>" already defined</code></dt> + <dd> + <p> + You have defined the id/name "<var>FOO</var>" more + then once. You will also get a message telling you where it was + first defined. Be aware that this message may be the result of an + ambiguity in the specification. While user-agents must treat + values of the id attribute as case-sensitive, they must still be + case-insensitive unique in the document. See + <a href="http://www.w3.org/TR/html4/struct/links.html#h-12.2.1">Section + 12.2.1 Syntax of anchor names</a> in the HTML 4.01 Recommendation + for further information. + </p> + </dd> + <dt id="unterm-comment-1"><code>entity end not allowed in comment</code></dt> + <dd> + <p> + Unterminated comment. The position indicator points to the very end of + the file, where the problem was detected; to find the beginning of the + comment, try searching for the last occurrence of + `<code><!--</code>' in the document. + </p> + </dd> + <dt id="unterm-comment-2"><code>name start character invalid: only s and comment allowed in comment declaration</code></dt> + <dd> + <p> + Unterminated comments again. This time, you have a case like: + </p> + <pre> + <!-- This is the first unterminated comment > + <!-- This is the second one > + </pre> + <p> + The validator (correctly) interprets the `<code>--</code>' in the + second comment as terminating the first comment, and then interprets + the text of the second comment as text between comments, which is not + allowed. + </p> + </dd> + <dt id="bad-comment"><code>unknown declaration type "<var>FOO</var>"</code></dt> + <dd> + <p> + Most likely an invalid comment of the form + <code><!invalid comment></code>; the validator is (correctly) + attempting to interpret it as an <a href="sgml.html#sgml">SGML</a> + markup declaration. + </p> + </dd> + <dt id="attr-quoted"><code>an attribute value must be a literal unless it contains only name characters</code></dt> + <dd> + <p> + You have an attribute whose value needs to be in quotes. If an + attribute value contains any character other than letters, digits, + hyphens and periods, it must be enclosed in double quotes (single + quotes would also be OK from an <a href="sgml.html#sgml">SGML</a> + standpoint, but some browsers don't recognize them). + </p> + </dd> + <dt id="attr-char"><code>character "X" not allowed in attribute specification list</code></dt> + <dd> + <p> + The validator has found a character inside an HTML tag that isn't + allowed there. This usually means you didn't put an attribute value in + quotes when necessary. It also probably means that the character in + question is not allowed in the value of the attribute at all, or you + would have received the <a href="#attr-quoted">previous error</a> + instead. See <a href="#bad-attr-char">below</a> for more information. + </p> + <p> + You can also get in trouble by forgetting the closing quote on an + attribute. For instance: + </p> + <pre> + <IMG SRC="http://foo.com/fred.gif> + <IMG SRC="http://foo.com/joe.gif> + </pre> + <p> + The validator will (correctly) interpret this as a SRC value of + <code>"http://foo.com/fred.gif> <IMG SRC="</code>, and then + choke on the following `:'. In this case, the position indicator in + the error message may be several lines below the line with the missing + quote. + </p> + </dd> + <dt id="name-length"><code>length of attribute value must not exceed LITLEN less NORMSEP (1022)</code></dt> + <dd> + <p> + This usually occurs in conjunction with the + <a href="#attr-char">previous error</a>. It almost always means that + you've forgotten a closing quote on an attribute value. For instance, + in: + </p> + <pre> + <IMG SRC="fred.gif> + <!-- 50 lines of stuff --> + <IMG SRC="joe.gif"> + </pre> + <p> + The SRC value for the first <code><IMG></code> is the entire + fifty lines of stuff up to the next double quote, which probably + exceeds the <a href="sgml.html#sgml">SGML</a>-defined length limit for + HTML string literals. Note that the position indicator in the error + message points to where the attribute value <em>ended</em> — in + this case, the <code>"joe.gif"</code> line. + </p> + </dd> + <dt id="undef-tag"><code>element "<var>FOO</var>" undefined</code></dt> + <dd> + <p> + You've used an unknown tag (represented here by "<var>FOO</var>"). Make sure the + DTD indicated by your DOCTYPE actually includes this element. + </p> + <p> + If the tag in question is a frame-related tag you must use the + "Frameset" DTD, and if you use (deprecated) physical markup ("FONT" + and friends) you must use the "Transitional" DTD. + </p> + </dd> + <dt id="not-allowed"><code>document type does not allow element "<var>FOO</var>" here</code></dt> + <dd> + <p> + Straightforward, but not terribly informative. There are a + <em>lot</em> of different errors that will generate this error + message: + </p> + <ul> + <li> + Using an unknown tag. In this case, the next error will be + <a href="#undef-tag">element "<var>FOO</var>" undefined"</a>. + </li> + <li> + Using a tag in the wrong place. For instance, + <code><TABLE><TD>blah</TABLE></code> will cause + this error. The trick here is that <code><TABLE></code> cannot + <em>directly</em> contain <code><TD></code>'s; it contains + <code><TR></code>'s which contain <code><TD></code>'s. + The above example should be + <code><TABLE><TR><TD>blah</TABLE></code>. + </li> + </ul> + </dd> + <dt><a id="not-contained" name="not-contained">document type does not allow element "<var>FOO</var>" here; assuming missing "<var>BAR</var>" start-tag</a>"</dt> + <dd> + <p> + Similar to the <a href="#not-allowed">previous error</a>, but more + specific: in this case, you have a "<var>FOO</var>" element that is not contained + in a "<var>BAR</var>" element when "<var>FOO</var>" is not allowed outside of "<var>BAR</var>". Some of the + most common causes of this error are: + </p> + <ul> + <li> + Using the <code>DD</code> element as a fake paragraph indent. + <code>DD</code> is not allowed outside of a <code>DL</code> element. + </li> + <li> + Improper construction of a nested list. An inner UL or OL in a + nested list may not appear directly within an outer UL/OL, but only + within an LI of the outer UL/OL, as in the following example: + <pre> + <OL> + <LI>Obtain the following items: + <UL> + <LI>Ham</LI> + <LI>Bread; one of: + <UL> + <LI>White</LI> + <LI>Rye</LI> + <LI>Whole wheat</LI> + </UL> + </LI> <!-- End of the "Bread" <LI> --> + <LI>Cheese</LI> + </UL> + </LI> <!-- End of the "Obtain" <LI> --> + <LI>Place ham and cheese between two slices of bread</LI> + <LI>Consume the resulting ham-and-cheese sandwich</LI> + </OL> + </pre> + <p> + The <code></LI></code> end tags are optional and are only + included above to emphasize how the structure of the nested list + is arranged; if you omit them, the parser will infer their + presence in the locations shown above. + </p> + </li> + </ul> + <p> + The validator has inserted a "<var>BAR</var>" start tag where it thinks there needs + to be one; it will probably complain later on that <a href="#no-end-tag">the + corresponding end tag is also missing</a>. + </p> + </dd> + <dt id="attr-undef"><code>there is no attribute "<var>FOO</var>" for this element (in this HTML version)</code></dt> + <dd> + <p> + You have used an attribute with an element that is defined not to have + that attribute. This is most commonly caused by using + vendor-specific attributes without setting the document type + appropriately. + </p> + </dd> + <dt id="undef-attr-val"><code>"<var>FOO</var>" is not a member of the group specified in the declared value of this attribute</code></dt> + <dd> + <p> + Similar to the <a href="#attr-undef">previous error</a>; this time, + you're using an attribute that is defined for the element, but with a + value that isn't defined for the attribute. For instance, the Netscape + extension <code><IMG ALIGN=ABSMIDDLE></code> will cause this + error; ABSMIDDLE isn't one of the allowed values for the ALIGN + attribute of <code><IMG></code> (unless, of course, you provided + a Netscape document type). + </p> + <p> + If you're using the Netscape document type, the BORDER attribute of + <code><TABLE></code> can cause this error. + </p> + <p> + This error can also be caused, oddly enough, by missing close quotes + on attribute values. For instance, given: + </p> + <pre> + <IMG SRC="fred.gif> <IMG SRC="joe.gif> + </pre> + <p> + The validator will (correctly) see a SRC attribute of + <code>"fred.gif> <IMG SRC="</code>, and then try to interpret + JOE.GIF as an attribute of <code><IMG></code>. + </p> + </dd> + <dt id="bad-attr-char"><code>syntax of attribute value does not conform to declared value</code></dt> + <dd> + <p> + Yet another attribute error; this time, the attribute in question was + defined to take a numeric value, or an <a + href="sgml.html#sgml">SGML</a> identifier value, and you used a + character that doesn't match what it was expecting. + </p> + <p> + One potentially annoying source of this error is the + <code>TD WIDTH</code> attribute. Whether intentionally or by oversight, + the HTML 3.2 DTD defines this attribute to have a value type of NUMBER, + which means that <code><TD WIDTH="50%"></code> is not allowed. + </p> + </dd> + <dt id="attr-bad-name"><code>value of attribute "<var>FOO</var>" invalid: "#" cannot start a name</code></dt> + <dd> + <p> + A special case of <a href="#bad-attr-char">the previous error</a>; the + attribute in question is defined to take as value an SGML name token, + which must begin with a letter. + </p> + </dd> + <dt id="bad-abbrev-attr"><code>"<var>FOO</var>" is not a member of a group specified for any attribute</code></dt> + <dd> + <p> + Another attribute error, this time referring to an "abbreviated" + attribute. <a href="sgml.html#sgml">SGML</a> allows you to omit the + name of an attribute if the attribute value is unambiguous. For + instance, <code><IMG ISMAP></code> is actually an abbreviation + of <code><IMG ISMAP=ISMAP></code>. (Technically, this also means + that e.g. <code><P ALIGN=CENTER></code> could be abbreviated to + <code><P CENTER></code>, but it is unlikely that current + browsers will get this right.) The validator has found something that + looks like an abbreviated attribute but doesn't match the value of any + attribute for this element. For instance, a typo like + <code><IMG ISNAP></code> would produce this error. + </p> + <p> + A missing close quote on a previous attribute value can also trigger + this error if the next quote it finds is followed by something that + looks like an abbreviated attribute; for instance, + <code><IMG SRC="fred.gif><IMG SRC="joe.gif></code> would + produce this error, referring to the "attribute value" <code>JOE.GIF</code>. + </p> + </dd> + <dt id="attr-missing"><code>required attribute "<var>FOO</var>" not specified</code></dt> + <dd> + <p> + You left off a required attribute of the indicated element. The most + common such omitted attribute is the <code>ALT</code> attribute of the + <code>AREA</code> or <code>IMG</code> element; browsers will typically + use these to build a menu equivalent to your client-side image map if + the user has disabled image loading, so you'll want to use a + meaningful value here. + </p> + </dd> + <dt id="no-end-tag"><code>end tag for "<var>FOO</var>" omitted, but its declaration does not permit this</code></dt> + <dd> + <p> + You forgot to close something. "<var>FOO</var>" is the element you forgot to close + (and the next message, `start tag was here' points to the particular + instance of "<var>FOO</var>" in question); the positional indicator points to where + the validator expected you to close the element. There are a few + common ways that this can happen: + </p> + <ul> + <li> + You've put something inside the "<var>FOO</var>" element that isn't allowed + there. For instance, + <code><UL><LI><H4>fake font change</H4></UL></code> + will cause this error, since headers aren't allowed inside <code><UL></code>'s; the + validator assumes that you meant to close the + <code><UL></code> before opening the <code><H4></code>. + </li> + <li> + Interlocked elements. For instance, + <code><B><I>nope</B></I></code> will cause + this error. HTML requires that you close elements inside-out + — that is, the last element you opened is the first element you should + close. In this example, you'd have to close the + <code><I></code> before the <code><B></code>. + </li> + <li> + Unclosed <code><A></code> tags. Yes, even + <code><A NAME="foo"></code> has to have a corresponding + <code></A></code>. Note that an empty + <code><A NAME></code> element won't be recognized by some browsers; be + sure to put at least a word or two inside the + <code><A></code>. + </li> + <li> + Having unadorned text where the validator was expecting a + sub-element of "<var>FOO</var>". For instance, + <code><DL>fake indent</DL></code> will produce this error, + since inside a + <code><DL></code>, the validator only expects to see + <code><DT></code>'s and <code><DD></code>'s. + </li> + <li> + A tag of the form <code><TABLE WIDTH=100%></code>. The + previous error should have been that the `%' was <a + href="#attr-char">"not allowed in attribute specification list"</a>. + What's happening here is that, in trying to get past the `%', the + validator has become confused and thinks the `%' is <em>inside</em> + the <code><TABLE>...</TABLE></code>, thus triggering the + error message for the previous reason. This error will likely be + followed by mistaken complaints that your <code><TR></code>'s + are <a href="#not-allowed">"not allowed here"</a>, plus a complaint + about your <code></TABLE></code> end tag. The solution is to + put the attribute value in quotes; ie. <code><TABLE + WIDTH="100%"></code>. + </li> + </ul> + <p> + In general, you should always explicitly close all elements and + quote all attribute values. + </p> + </dd> + <dt id="floating-close"><code>end tag for element "<var>FOO</var>" which is not open</code></dt> + <dd> + <p> + The validator found an end tag, represented here by "<var>FOO</var>", without a + corresponding start tag. This frequently occurs in conjunction with + the <a href="#no-end-tag">previous error</a>. For instance, given + <code><B><I>nope</B></I></code>, the validator + will insert a <code></I></code> before the + <code></B></code>, and then will find the + <code></I></code> after the <code></B></code> and will + have nothing to match it with. + </p> + <p> + A subtle variation of this is <code><P><H4>fake font + change</H4></P></code>. <code><H4></code>'s aren't + allowed inside <code><P></code>'s, but since HTML allows you to + omit the <code></P></code> end tag for paragraphs, the validator + assumes that you meant <code><P></P><H4>fake font + change</H4></P></code>, in which case the final + <code></P></code> is indeed superfluous. + </p> + <p> + This error can also be caused by incorrectly supplying an end tag for + "empty" elements like <code><HR></code>, <code><BR></code> + or <code><IMG></code>. + </p> + </dd> + <dt id="omitted-content"><code>end tag for "<var>FOO</var>" which is not finished</code></dt> + <dd> + <p> + You have a "<var>FOO</var>" element, but you have omitted some required sub-element + of it. For instance, a <code>TABLE</code> with no <code>TR</code>'s + would cause this error. + </p> + </dd> + <dt id="no-start-tag"><code>start tag for "<var>FOO</var>" omitted, but its declaration does not permit this</code></dt> + <dd> + <p> + The validator expected you to start a "<var>FOO</var>" element at the indicated + point. This probably means you've put unadorned text somewhere it + isn't allowed; for instance, <code><UL>fake + indent</UL></code> will cause this error. + </p> + </dd> + <dt id="bad-entity"><code>unknown entity "<var>FOO</var>"</code></dt> + <dd> + <p> + The validator has found an entity (something like + <code>&this;</code>) that it doesn't recognize. There are a few + possibilities: + </p> + <ul> + <li> + <p> + A reference to a URI that uses <code>&</code> as a separator + between parameters, such as + "<code>http://example.org/prog?x=1&y=2</code>". + </p> + <p> + To solve this problem, simply replace all the <code>&</code>'s + in attribute values with <code>&amp;</code> (user agents will + convert them back before following the links.) + </p> + <p> + Another way to get around this problem is for the author of the CGI + program to allow a different value to be used between arguments, + like ';' or '|', which would allow the link to be coded as e.g. + <code><a href="http://example.org/prog?x=1;y=2"></code> + </p> + </li> + <li> + An unterminated entity; for instance, <code>this&ampthat</code> + for "this&that", which the validator (correctly) interprets as a + request for the entity <code>&ampthat;</code>. Technically, any + non-alphanumeric character (such as a space) will suffice to + terminate the entity, but some browsers get this wrong; the safest + thing to do is to terminate all entities with a semicolon, turning + our example into <code>this&amp;that</code>. + </li> + <li> + The entity <code>&quot;</code> in conjunction with the HTML 3.2 + <code>DOCTYPE</code>. This entity was <a + href="http://lists.w3.org/Archives/Public/www-html/1997Mar/0003.html">accidentally + omitted</a> from the most recent version of the HTML 3.2 DTD. You + should be able to ignore this error safely, though if you wish, you + can replace <code>&quot;</code> with the equivalent character + entity <code>&#34;</code>. + </li> + </ul> + </dd> + <dt id="bad-char"><code>non SGML character number ###</code></dt> + <dd> + <p> + You've used an illegal character in your text. HTML uses the standard + ISO8859-1 character encoding, and ISO8859-1 leaves undefined 65 + character codes (0 to 31 inclusive and 127 to 159 inclusive); the + validator has found one of these undefined characters in your + document. The character may appear on your browser as a curly quote, + or a trademark symbol, or some other fancy glyph; on a different + computer, however, it will likely appear as a completely different + character, or nothing at all. + </p> + <p> + Your best bet is to replace the character with the nearest equivalent + ASCII character, or to use an appropriate <a + href="http://www.w3.org/hypertext/WWW/MarkUp/html3/latin1.html">character + entity</a>. For more information on ISO8859-1, see <a + href="http://ppewww.ph.gla.ac.uk/%7Eflavell/aflavell.html">Alan + Flavell</a>'s excellent <a + href="http://ppewww.ph.gla.ac.uk/%7Eflavell/iso8859/">ISO8859-1/HTML + reference</a>. + </p> + <p> + This error can also be triggered by formatting characters embedded in + documents by some word processors. If you use a word processor to edit + your HTML documents, be sure to use the "Save as ASCII" or similar + command to save the document without formatting information. + </p> + </dd> + <dt id="bad-pub-id"><code>cannot generate system identifier for entity "HTML"</code></dt> + <dd> + <p> + Your <code>DOCTYPE</code> declaration contains a public identifier + that the validator doesn't recognize. See the <a + href="sgml.html#doctype">discussion of <code>DOCTYPE</code></a> for an + explanation of what's happening, and what public identifiers the + validator recognizes. + </p> + </dd> + <dt id="missing-subel"><code>missing a required sub-element of "<var>FOO</var>"</code></dt> + <dd> + <p> + The element "<var>FOO</var>" is defined to <em>require</em> one or more + sub-elements. One example is TR which requires one or more TD or TH + elements. + </p> + </dd> + <dt id="start-tag"><code>start tag was here</code></dt> + <dd> + <p> + Not an error, but rather a pointer to the start tag of the element + the previous error referred to. + </p> + </dd> + <dt id="text-not-allowed"><code> text is not allowed here; try wrapping the text in a more descriptive container</code></dt> + <dd> + <p> + The document contained bare text where an element was expected. + For instance, you must wrap text in <code><p></code> if it + appears directly inside the <code><body></code>. + </p> + <p> + This error may also indicate an unquoted attribute value containing + a reserved character (such as "<samp>/</samp>") which terminates the + attribute. The net effect is that the rest of the attribute value + appears to be plain text, outside any element, to an SGML parser. + </p> + </dd> + <dt id="unkn-att-val"><code> value of attribute "<var>FOO</var>" cannot be "<var>BAR</var>"; must be one of "<var>FOO</var>", "<var>BAR</var>", "<var>BAZ</var>"</code></dt> + <dd> + <p> + An attribute was specified to contain one of a set of predefined + values and you have used a value that is not in that set. The error + message tells which attribute value was unknown and the possible + legal values for this attribute. + </p> + </dd> + <dt id="no-attr-end"><code>character "<var>FOO</var>" not allowed in attribute specification list possibly caused by a missing quotation mark ending a previous attribute value</code></dt> + <dd> + <p> + A character that is illegal in the attribute list for a particular + attribute was encountered. It's is likely that this is a result of + a missing quote character on a previous attribute value. + </p> + </dd> + <dt id="dup-attr"><code>duplicate specification of attribute "<var>FOO</var>"</code></dt> + <dd> + <p> + You have specified an attribute more than once. For instance, you've + used the "height" attribute on the "img" element twice on the same + "img" tag. + </p> + </dd> + <dt id="invalid-attr-val"><code>invalid attribute value</code></dt> + <dd> + <p> + The value of this attribute is not a legal value for attributes. For + instance, the attribute cannot be the empty string. This is distinct + from errors related to illegal values for a specific attribute. + </p> + </dd> + <dt id="attr-spec-nmtoken"><code>an attribute specification must start with a name or name token</code></dt> + <dd> + <p> + An attribute name (and some attribute values) must start with one of + a restricted set of characters. This error usually indicates that + you have failed to add a closing quotation mark on a previous + attribute value (so the attribute value looks like the start of a + new attribute) or have used an attribute that is not defined + (usually a typo in a common attribute name). + </p> + </dd> + <dt id="inval-comment"><code>invalid comment declaration; check your comment syntax</code></dt> + <dd> + <p> + There is a syntax error in an SGML Comment Declaration. This may be + caused by too many or too few hyphens "-" or that you have included + an invalid character in the comment. The next message will be + "comment declaration started here". + </p> + </dd> + <dt id="assuming-missing-starttag"><code>element "<var>FOO</var>" not allowed here; assuming missing "<var>BAR</var>" start-tag</code></dt> + <dd> + <p> + The referenced element "<var>FOO</var>" isn't allowed in the context it occurs + in, but it would be if it was wrapped in a "<var>BAR</var>" element. The + Validator has assumed that you have forgotten to add a "<var>BAR</var>" + start tag and continued validation as if it was there. You should + check if this is the case and insert the proper tag. + </p> + </dd> </dl> - <!--#include virtual="../footer.html" --> </body> </html> |