How does the table extension work? (e.g. ALTER TABLE MEDIUMINT to INT(10))

[k00ni]

There are code parts which alter tables by changing the datatype from MEDIUMINT to INT(10), like here:

https://github.com/semsol/arc2/blob/master/store/ARC2_StoreTableManager.php#L86

Can you tell me, when these "extensions" are used? Are they still required? My current approach would be to change the datatype from MEDIUMINT to INT(10) directly in the CREATE TABLE queries.

@semsol