Manual:Change tag def table/en

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

Schema summary
+--+-+--+-+-++ +--+-+--+-+-++ +--+-+--+-+-++
 * Field           | Type                | Null | Key | Default | Extra          |
 * ctd_id          | int(10) unsigned    | NO   | PRI | NULL    | auto_increment |
 * ctd_name        | varbinary(255)      | NO   | UNI | NULL    |                |
 * ctd_user_defined | tinyint(1)         | NO   | MUL | NULL    |                |
 * ctd_count       | bigint(20) unsigned | NO   | MUL | 0       |                |