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| author | link <link@localhost> | 2001-02-23 09:06:49 +0000 |
|---|---|---|
| committer | link <link@localhost> | 2001-02-23 09:06:49 +0000 |
| commit | 1455eff94f527f606b7e360258fa3774731528d7 (patch) | |
| tree | f5e1a6c0fb011a12c5371b646486ff9dbad4a887 /htdocs/docs/errors.html | |
| parent | 0d8ea0eb2b620b0ab52500d3d52f7cd3d8acf787 (diff) | |
| download | markup-validator-1455eff94f527f606b7e360258fa3774731528d7.zip markup-validator-1455eff94f527f606b7e360258fa3774731528d7.tar.gz markup-validator-1455eff94f527f606b7e360258fa3774731528d7.tar.bz2 | |
Checking in documentation. Mostly just importing (cleaned up versions of)
Scott Bigham's original FAQ/docs. New additions: a User Manual and information
for developers. All files use the (also new) base stylesheet.
Diffstat (limited to 'htdocs/docs/errors.html')
| -rwxr-xr-x | htdocs/docs/errors.html | 549 |
1 files changed, 549 insertions, 0 deletions
diff --git a/htdocs/docs/errors.html b/htdocs/docs/errors.html new file mode 100755 index 0000000..85c49aa --- /dev/null +++ b/htdocs/docs/errors.html @@ -0,0 +1,549 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> + + <head> + <title>W3C HTML Validation Error Messages</title> + <link rev="made" href="mailto:gerald@w3.org" /> + <link rel="stylesheet" type="text/css" href="/base.css" /> + <meta name="keywords" content="HTML, Hypertext Markup Language, Validation, W3C HTML Validation Service" /> + <meta name="description" content="W3C's easy-to-use HTML validation service, based on an SGML parser." /> + <meta name="revision" content="$Id: errors.html,v 1.1 2001-02-23 09:06:49 link Exp $" /> + <meta name="modified" content="$Date: 2001-02-23 09:06:49 $" /> + </head> + + <body bgcolor="#FFFFFF" text="#000000" link="#0000ee" vlink="#551a8b"> + <h1><a href="http://www.w3.org/"><img align="left" + src="http://www.w3.org/Icons/WWW/w3c_home" height="48" border="0" + alt="W3C" /></a> HTML Validator Error Messages</h1> + <p align="right" class="navbar"> + <a href="about.html">About this service</a> | + <a href="whatsnew.html">What's new</a> | + <a href="source/">Source code</a> | + <a href="feedback.html">Feedback</a><br clear="right"/> + <a href="file-upload.html">Upload files</a> | + <a href="http://lists.w3.org/Archives/Public/www-validator/">www-validator archives</a> | + <a href="http://jigsaw.w3.org/css-validator/">CSS validator</a> | + <a href="checklink">Link checker</a><br clear="right"/> + <a href="http://www.w3.org/People/Raggett/tidy/">HTML Tidy</a> | + <a href="http://www.w3.org/MarkUp/">HTML home</a> | + <a href="http://www.w3.org/TR/html401/">HTML 4.01</a> | + <a href="http://www.w3.org/TR/xhtml1/">XHTML 1.0</a> + <br clear="all" /> + </p> + + <dl> + <dt id="unterm-comment-1">"entity end not allowed in comment"</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">"name start character invalid: only s and comment allowed in comment declaration"</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">"unknown declaration type `FOO'"</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">"an attribute value must be a literal unless it contains only name characters"</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 okay from an <a href="sgml.html#sgml">SGML</a> + standpoint, but some browsers don't recognize them). + </p> + </dd> + <dt id="attr-char">"character `X' not allowed in attribute specification list"</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">"length of attribute value must not exceed LITLEN less NORMSEP (1022)"</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">"element `FOO' undefined"</dt> + <dd> + <p> + You've used an unknown tag (represented here by FOO). 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">"document type does not allow element "FOO" here"</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 `FOO' 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 id="not-contained">document type does not allow element "FOO" here; assuming missing "BAR" start-tag</dt> + <dd> + <p> + Similar to the <a href="#not-allowed">previous error</a>, but more + specific: in this case, you have a FOO element that is not contained + in a BAR element when FOO is not allowed outside of BAR. 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 BAR 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="not-allowed-contained">"document type does not allow element "FOO" here; assuming missing "BAR" start-tag"</dt> + <dd> + <p> + Similar to the <a href="#not-allowed">previous error</a>, but more + specific: in this case, you have a FOO element that is not contained + in a BAR element when FOO is not allowed outside of BAR. Probably the + most common cause of this error is the use of the <code>DD</code> + element as a fake paragraph indent; <code>DD</code> is not allowed + outside of a <code>DL</code> element. + </p> + <p> + The Validator has inserted a BAR 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="undef-attr">"there is no attribute `FOO'"</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">"`FOO' is not a member of the group specified in the declared value of this attribute"</dt> + <dd> + <p> + Similar to the <a href="#undef-attr">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">"syntax of attribute value does not conform to declared value"</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="bad-name-attr">"value of attribute "FOO" invalid: "#" cannot start a name"</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">"`FOO' is not a member of a group specified for any attribute"</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="missing-attr">"required attribute `FOO' not specified"</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> element; browsers will typically use these to build + a menu equivalent to your client-side imagemap if the user has + disabled image loading, so you'll want to use a meaningful value here. + </p> + </dd> + <dt id="no-end-tag">"end tag for `FOO' omitted, but its declaration does not permit this"</dt> + <dd> + <p> + You forgot to close something. FOO is the element you forgot to close + (and the next message, `start tag was here' points to the particular + instance of FOO 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 FOO 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 FOO. 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">"end tag for element "FOO" which is not open"</dt> + <dd> + <p> + The Validator found an end tag, represented here by FOO, 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">"end tag for `FOO' which is not finished"</dt> + <dd> + <p> + You have a FOO 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">"start tag for `FOO' omitted, but its declaration does not permit this"</dt> + <dd> + <p> + The Validator expected you to start a FOO 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">"general entity `FOO' not defined and no default entity"</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> + 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/msg00636.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> + <li> + The entity <code>&nbsp;</code> in conjunction with the Mozilla + <code>DOCTYPE</code>. WebTechs' Mozilla DTD, which The Validator + uses, inexplicably does not define this entity. This error message + should not cause a problem, though you may wish to switch to the + equivalent but more widely handled character entity + <code>&#160;</code>. + </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> + <p> + A URL for a CGI program that uses `&' as a separator, such as + "<code>http://host/prog?x=1&y=2</code>". This is a common + problem: the inventors of CGI didn't think things through very + carefully when they decided to use the '&' character as a + separator between CGI arguments, because '&' has special + status in HTML. The only way to get around this is for the author + of the CGI program to use a different value between arguments, + like ';' or '|', which would allow the link to be coded as + <code><img src="http://site/cgi?opt1=val1;opt2=val2"></code> + or whatever. + </p> + <p> + Please contact the maintainer of the CGI program you are linking + to, and ask them to use a different character for their separator. + (Normally this is extremely easy to add to the CGI program; + multiple characters can also be used so existing links using the + '&' character will still work.) + </p> + </li> + </ul> + </dd> + <dt id="bad-char">"non SGML character number ###"</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="unicode-char">"`####' is not a valid character number"</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 id="bad-pub-id">"cannot generate system identifier for entity `HTML'"</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> + </dl> + </body> +</html> |