A Rexx program contains one or more executable code units.
Directive instructions separate these executable units. A
directive begins
with a double colon (::) and is a nonexecutable instruction. For example,
it cannot appear in a string for the INTERPRET instruction to be interpreted.
The first directive instruction in a program marks the end of the main executable
section of the program.
For a program containing directives, all directives are processed first
to set up the program's classes, methods, and routines. Then any program code
in the main code unit (preceding the first directive) is processed. This code
can use any classes, methods, and routines that the directives established.
