Wikimedia Bugzilla is closed!

If a (sub)headline starts with a number, it gets an id attribute that starts with a number, too, although NameStartChar http://www.w3.org/TR/REC-xml/#NT-NameStartChar doesn't allow it.

For example:

Ethernet_physical_layer:355: element span: validity error : Syntax of value for attribute id of span is not valid
it Ethernet">edit</a>]</span> <span class="mw-headline" id="10_gigabit_Ethernet"
                                                                               ^
Possible solution: Prepend an underscore it the headline doesn't start with a NameStartChar, or almost any of the solutions proposed for bug 7356