GOt a message telling me that empty tags are for "HMTL 4.01 Strict" and that I should use it only in XHTML.

I'm pretty sure there is no language "HMTL" and that if they really meant "HTML" then that would be maladvice.

Message:
"The sequence <FOO /> can be interpreted in at least two different ways, depending on the DOCTYPE of the document. For HMTL 4.01 Strict, the '/' terminates the tag <FOO (with an implied '>'). However, since many browsers don't interpret it this way, even in the presence of an HMTL 4.01 Strict DOCTYPE, it is best to avoid it completely in pure HTML documents and reserve its use solely for those written in XHTML. "