Manual:Change tag def table

The change_tag_def table is a table defining tag names for IDs. It also stores hit counts to avoid expensive queries on.

ctd_id
Numerical ID of the tag ( refers to this)

ctd_name
Symbolic name of the tag (what would previously be put in )

ctd_user_defined
Whether this tag was defined manually by a privileged user using Special:Tags

ctd_count
Number of times this tag was used