different printers support different commands for pause ... "players" too, so if you are using for e.g. octoprint to send g-code to the printer M0 will be handled by the octoprint .. if you for e.g. have on the other side the smoothieware you want to send "suspend" or "m600" *before* you send M0 and when you are done with your "pause" you then need to send "M601" or "resume" before you tell octoprint to resume (by clicking play).
What I'd like is to return to the OP's question, there are multiple processes and between processes one want to pause to do whatever (push in a trapped nut, switch filament, pour liquid plastic into a prepared hole...)... using the REPLACE thingy in post processing script helps but it's a huge pita
if I change layer height of the process I then need to go recalculate where I want the stop and put it in the postprocessing ... if I change *other* process it can still hurt me so this REPLACE thingy don't work in real life
when you use multi processes, especially if you use them to their full potential. It's a crouch that kinda works if you have single process, and it's a bad crouch, hard to use, very imprecise
Now, if we look at scripts there are "starting script", "tool change script" and "ending script". Unfortunately "starting script" is used not for each process but only for the "first" process, also the "ending script" works only for the very end of the output of whole script so only for the "last" process. If S3D would use the "starting script" and "ending script" as something that's prepended and appended to a process (as one would expect) there would be easy solution to this question. Maybe in future, who knows, they add this.
Now the tool change script, if it not in the "first" process, it's not even in the header of the gcode
(or maybe that was because I have no tool changes and only one tool defined) ... anyhow probably one could set process1 to run with tool0 and process2 to run with tool1 and somehow tell s3d that both tool0 and tool1 are the same extruder0 and then use the "tool change script" to insert the g-code but I didn't manage to get that going after few min of playing with it
It is IMO a serious feature missing in s3d and "replace" workaround is not nearly covering the requirements
integrates with Simplify3D and allow you to
Calculate print time accurately (acceleration, max speed, junction deviation all taken into consideration)
Embed M117 codes into G-Code
Upload your G-Code directly to Octoprint
open source and unlicence