A match-keys argument is a list of length equal to the number of primary keys. The match-keys restrict the actions of the table command to those records whose primary keys all satisfy the corresponding element of the match-keys list. The elements and their actions are:
- The false value matches any key in the corresponding position.
- an object of type procedure
- This procedure must take a single argument, the key in the corresponding position. Any key for which the procedure returns a non-false value is a match; Any key for which the procedure returns a
- other values
- Any other value matches only those keys