I am attempting to use a custom DTD to validate my XHTML pages, using the validator at http://www.htmlhelp.com/tools/validator/. I need to do this to take account of the <embed> tag that I am using in the pages.

I've figured out how to do most things, and have got the whole page validating - including <embed> - with the exception of some of the lines in the <head> tag. If I copy the same lines and validate them against the "official" XHTML DTD they are okay, and AFAICT my DTD is identical in the relevant sections. Can anyone explain in more detail what the following errors are actually saying?

Line 6, character 44:

... uiv="expires" content="now" />
^
Error: text is not allowed here; try wrapping the text in a more descriptive container

* Line 13, character 51:

... t" href="/~css/default.css" />
^
Error: text is not allowed here; try wrapping the text in a more descriptive container