<b>To me the Term "FORCE PLAY SLIDE RULE" means you are required to slide on a force play.</b>

That would be Forced Slide Rule. Force Play, refers to the play, not the slide. Fed does not require a slide, ever.

When this rule first came in, the Points of Emphasis called it the FPSR; so did the FED Rules slides. I even think there was a heading in the Rule Book with that wording. Naturally, there were the predictable rats thinking that it was a Forced Slide Play Rule, even tho' the "never required to slide" language was there from the start. The FPSR has been around long enough that some [most] of the references have been cleaned out of the book, but if you've "never heard it called that", check out the top of page 55 in th '05 Rule Book [8-4-2 PENALTY]: ...On a force-play slide with less than two outs, ....[my emphasis].

All slides must be legal. On every slide the runner can't roll block into the fielder, can't pop-up into the fielder, must have the leading foot below the knee, etc.

On a force play, there are extra requirements -- must be in a direct line to the base (or away from the fielder), can't go beyond the base and make contact. There are also extra penalties -- two are out.

You are correct however, that it should more properly be called the Force-Play Slide Rule.

When in FED rules is it stated that the runner can be called out and the run is nullified AFTER he touches home plate in this situation?

See 2.32.2C and 8.4.2Y (for the force play situation).

See 2.21.1B (for the non-force play situation)