11.1.1. Actions of prepare_prolog
The following parameters are made visible to the NGC procedure:

#<tool> - the parameter of the T word

#<pocket> - the corresponding pocket

If tool number zero is requested (meaning Tool unload), the corresponding pocket is passed as -1.

It is an error if:

no tool number is given as T parameter

the tool cannot be found in the tool table.

Note that unless you set the [EMCIO] RANDOM_TOOLCHANGER=1 parameter, tool and pocket number are identical, and the pocket number from the tool table is ignored. This is currently a restriction.

11.1.2. Actions of prepare_epilog