Programming an Engraving to allow Machinist to modify Engraving

Hey everyone,
I am having issues creating a program or really just understanding how to create the program for an engraving that will allow the operator to modify the text being engraved. Some time in the past I worked with a great programmer who had created this in a part we had ran. I myself have not been able to recreate that since and am now stuck in a situation where we will need it for a production order. We currently have a need to create a traceability number on our parts that is specific to customer purchase order, and this number will change each run. Rather than manually have the machinist part mark we would like to have the program use a macro possibly that offers an engraving that can be modified. I hate literally asking for someone to just do something for me, I would love if someone could explain the science behind how it works so I could have a great understanding of how it works. I feel like I understand in principle what we want to do but cannot put it to code. I will include a picture and maybe that will offer some additional context.

The arrow is point to a text that will change on each run, but the remaining text will not. Please if anyone can offer help that would be greatly appreciated.

https://www.cnczone.com/forums/attac...d=462480&stc=1