Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 753)

Paramacros
Chapter 28
28-53
These macros are executed only as non-modal macro.
The execution of the T--, S--, or B--code macro calls is the same as M-code
macro calls with the following exceptions:
the parameter # referenced when called
the macro program called
T calls macro 9000
S calls macro 9029
B calls macro 9028
In order for the T--, S--, or B--words to call up a macro program, these
prerequisites must be met:
1. The value following the word must be equal to the value stored for
the specified parameter #.
For example:
T14;
The value of 14 must have been previously stored as the value for the
parameter #149.
2. An AMP flag for that specific word must be turned on by the system
installer to allow that word to call a macro.
3. The value for an AMP-defined T--, S--, or B--code command has the
same format and range as an ordinary T--, S--, or B--code.
Nesting occurs when one program calls another program. A subprogram
called by a main program is an example of nesting. (The “nested” program
is the program called.)
Nesting applies to macros as well. When the main program calls a macro,
the macro is said to be on nesting level 1. If this macro in turn calls
another macro, this second macro is said to be in nesting level 2. Macros
may be nested up to a maximum of 4 levels. However, if the maximum
number of nested paramacros (4) is combined with up to 4 subprograms
that end with M98, a maximum of 8 levels of nesting can be programmed.
What is not counted as an additional nested level? When a lower nested
macro with a modal feature forces a higher nested macro to call it, the
number of nested levels does not increase. Nor does it increase when a
subprogram is called using M98.
28.6.7
Nesting Macros