100 above minimums
" The path is built from the lowest constraint upwards, assuming idle thrust"
That's a quote from one one of the Boeing 737 manuals...I'm not going to give you a reference, maybe whilst looking for it you might learn some other useful stuff, I'm assuming you work for an airline and have the manuals available to you.
Thinking of an example, if you have a long SID and fifty miles to the FAF which is probably the lowest altitude constraint, then you will be at an altitude which matches that distance for an idle path descent, if your programming on the descent forecast page is accurate. If you suddenly get a short cut and put DTO the FAF and now have thirty miles to go instead of fifty then it's going to tell you you're high, because you are.
It's all in the manuals, try reading and learning instead of asking here, or ask the next training captain/check airman you get to fly with, or email your training department. Unfortunately you can never be sure that pprune users are even real pilots nowadays, I could have just made all of that up.