Select 3D Rest Laser Engraving if you want to create a laser toolpath to engrave data into a previously machined part.
ArtCAM needs two reliefs. The current relief should represent the part after it has been engraved. You can then use the Rest Engraving area to load a base relief which represents the part before the engraved decoration has been added. ArtCAM then calculates the laser toolpaths to machine the difference between the two reliefs.