I gather we are talking about Ram Concept for a Post-tensioned slab designed to EC2. I assume the tendons have been modeled without jacks, so they are under a constant axial force (for details, see "About Jacks" in the program manual). When it comes to service stress we are treating those tendon forces and an external load and then evaluating the net stress acting on the sections (sections of a design strip usually) and comparing those net stresses against code limits.
Here are a few other code sections that should help:
30.2.5 Viewing post-tensioning precompression (P/A)
30.2.8 Viewing section stresses
53.1.7 Tendons – External Load or Internal Force?
Here are a few other code sections that should help:
30.2.5 Viewing post-tensioning precompression (P/A)
30.2.8 Viewing section stresses
53.1.7 Tendons – External Load or Internal Force?