XHTML Validation - Tidy Warning: <a> cannot copy name attribute to id

this happens at the page that list the questions per category, and possibly others.

Cause:
In XHTML, the "name" attribute has been deprecated and replaced by the "id" attribute. If you want to keep both tags for compatibility reasons, the values should be the same. This error is generated when only the "name" attribute exists and that tidy try to copy the value of the name in the id attribute. But an "id" must begin with a letter (A-Za-z).
Solution:
Use "id" instead of "name" or use both with identical values.
Note that an "id" must begin with a letter (A-Za-z).