Auto-increment columns are equivalent to identity columns in those DBMS that support identity columns.
If you switch from Sybase ASA to a DBMS that supports identity columns, the Identity checkbox will be selected for each auto-increment column. On the other hand, if you switch to Sybase ASA, identity columns will be assigned the autoincrement default value.
When you reverse engineer a script containing identity columns (using Sybase ASE-compatible syntax), these are automatically converted into auto-increment columns in Sybase ASA.