)CS followed by an integer from 0 to 7 establishes APL.68000 Level I or Level II mode. The Compatibility Setting is a workspace parameter and defaults to 0. See ŒCS for details of the parameters. For example,
)CS 0 1 2 3[2]
generates a RANK ERROR whilst Compatibility Setting 1 (APL.68000 Level I mode) will return the result 2 for the same expression. The Compatibility Setting is a workspace parameter and defaults to 0