>No they are not interchangable. They are interchangable for array elemets only. () will not work on strings, while [] will not work on proc / method etc.

As I stated already elsewhere in this thread, the square brackets do work with functions/methods . Not that I would recommend to use them in such manner.

? myfunc(), myfunc[]

o = CREATEOBJECT("Test")
? o.MyMethod(), o.MyMethod[]

RETURN

FUNCTION myfunc()
RETURN DATE()

DEFINE CLASS Test AS Custom
FUNCTION MyMethod
RETURN DATETIME()
ENDDEFINE