How do you assign a global var in a CAS function?

[webmasterpdx]

e.g., if you use EXPORT as below...

#cas
TEST(l):=
BEGIN
EXPORT MMM:=256;
RETURN l[3];
END;
#end

...it compiles OK, but when you try to run TEST(L1), it'll give a bad argument error.
However, if you comment out the EXPORT statement, it'll work fine.

How do you create a global variable in a CAS function if EXPORT doesn't work?

Thanks
-Donald