1 point safety

[gopher2]

In the table for Rule 8-1 "Point Values" it says that when a team tries for the point(s) after a TD that the touchdown (2 point play) is worth 2 points, and a field goal or safety is worth 1 point.  Field goal is kicking the EP, but how would a 1 point safety be awarded.  I've seen 1 point safety in multiple college games, but I thought it was impossible in high school  since a ball is dead in the end zone when the defense obtains possession through an interception or recovery of a ball fumbled into the end zone?

[Bobref]

Team A lines up for a 2 pt. try. A3 takes the handoff and fumbles. The ball is lying at rest on the 2 yd. line. B2 attempts to recover it, but muffs it and it goes into the end zone, where B6 falls on it. B2’s muff is a new force which was responsible for the ball being in B’s end zone where it was declared dead in B’s possession. Result is a safety. 1 pt. because it was during a try.

[gopher2]

This is a high school rule?  Just curious when it was put in the books or have I just never paid attention?  Also because it is a force-based rule, if the ball was just bouncing around due to A's fumble (not at rest), but it bounced off of B into the end zone...then A could recover in the end zone for 2 points or B could recover in the EZ for 0 points?