Only in cases where GNU's assembler format conflicts with that of the CodeWarrior assembler does the GNU Compatible Syntax option have any effect. Specifically:
Whether defined using .equ or .set, all equates can be re-defined.
The .type directive ignored.
Undefined symbols are automatically treated as imported
< and > mean left-shift and right-shift instead of less than and greater than.
! means bitwise-or-not instead of logical not.
Precedence rules for operators are changed to be compatible with GNU rather than with C.
Local labels with multi-number characters are supported (example: "1000:"). There is no limit on the number of digits in the label name. Multiple instances of the label are allowed. When referenced, you get the nearest one - forwards or backwards depending on whether you append 'f' or 'b' to the number.
Numeric constants beginning with 0 are treated as octal.
Semicolons can be used as a statement separator.
A single unbalanced quote can be used for character constants. For example: .byte 'a