A fumble is defined as either loss of possession of the ball or failure to gain possession on a kick return where the ball is touched. A player generally should not be charged with a fumble if that player recovers his own fumble immediately and the defence is deemed to have had no chance for a recovery. However, if it is a flagrant fumble and opposing players have an opportunity to recover it, a fumble should be charged.
The act of merely touching the ball is not necessarily considered to be possession. On the greased-pig type of scrambling for a fumbled ball, charge the original player for the fumble and credit the eventual recovery to the player who winds up with the ball. Ignore all momentary touching in between.
On a play where a fumble is charged, yards gained/lost to the point of recovery are credited to the player who fumbled. Offensive players advancing an own team fumble recovery will be credited with those yards.