underline in NC macro

Hello

everyone I want to insert a NC macro into a process run in order to occupy a zero point with keyed values. Joker is a Siemens 840D PL.
It should look like this:
*STOPRE
*R13=R143-3
*R21=-R13+329
*R31=-R21
*STOPRE
*$P_UIFR[1,Z,TR]=R13
*$P_UIFR[2,X,TR]=R21
*$P_UIFR[3,X,TR]=R31
*STOPRE

It works well so far apart from the underline between $P and UIFR. It’s not given out in the NC program.
In there is simply an empty space. However it’s really necessary for the instruction.
Does anybody have an idea how to insert it?

Thank you very much

So
If anybody is interested here the solution:
Place a % before the empty space... then it works.
Maybe it helps anybody as well!