[loc03]
No element may point to a TAN file that has an identical @id value; the only exception is a <see-also> pointing to an older or new version.
@id
<see-also>
Affects: <location> <inclusion> <see-also> <source> <key>
<location>
<inclusion>
<source>
<key>
Used by template ŧ check-referred-doc
ŧ check-referred-doc