"less-than" in attribute value

[anionic]

My XHTML 1.0 handbook says: "WARNING: ... It is illegal to have a less-than character in an attribute value, even if it is encoded using an entity reference." and advises encoding < as &#60;

The W3C free online checker also complains about this (which is how I became aware of this, when a client checked a site we did for them).

How can I configure 9.0 to check for this? Here is a test page:

http://jbgb.com/docs/test1.html

[Albert Wiersch]

This is interesting. I haven't had this issue come up before. I see from your test page that the W3C validator doesn't like:

Code: Select all

<meta name="author" content="me <grin>" />

...but I am not aware of any real-life situations where it would be a problem, and real-life is important to CSE HTML Validator.

Furthermore, the included DTD based validator in CSE HTML Validator doesn't mind this either, though this may be one of its XHTML limitations.

I also found it hard to find anything on the web about this. Do you have any links?

Unfortunately I cannot think of an easy way to have CSE HTML Validator generate messages for this issue for all attribute values.

I could perhaps add an option to check for this in the next major version of CSE HTML Validator.

[Albert Wiersch]

In the next V10 BETA, this warning message will now be generated for unescaped less-than characters in attribute values in XHTML documents:
Found at least one unescaped less-than character ('<') in an attribute value in an XHTML type document. In XHTML (but not in HTML), less-than characters in attribute values should be escaped with "&lt;" or "&#x3c;". However, no real-world browser or user agent is currently known to have a problem with unescaped less-than characters in attribute values.

Thanks!