David and Greg are playing stableford.
They are playing a Par 4 where both have 1 handicap stroke.
Both balls are on the putting green. David has had 5 strokes and Greg has had 4 strokes.
David putts and his ball comes to rest well to the right of the hole but still on the putting green (not on Greg's intended line of play or in a possible backstop position).
David's score is zero points for the hole and his hole is completed.
David leaves his ball where it is and Greg then putts.
His errant putt strikes David's ball and Greg's ball is deflected into the hole.
Greg retrieves his ball from the hole and both players start the next hole.
Greg scores 2 stableford points for the hole.     [REF: 6S1228]

Liz says to Jill during a play stoppage.
"An obstruction (within the Rules of Golf) is any artificial object except for integral objects or boundary objects"       [REF: 6S1147]

David and Greg are playing stroke.
David's tee stroke is on the putting green (is marked and lifted) and Greg's tee stroke has come to rest just short of the putting green (general area).
Greg gets David to move his marker a club-head to the right. Greg then chips and his ball comes to rest to the right of the hole but on the putting green.
David now putts using the current position of his marker (marker removed first of course). His errant putt strikes Greg's ball and David's ball is deflected close to the hole.
David frustratingly knows he gets a 2-stroke penalty for striking Greg's ball.
David taps his ball (using the grip of his putter) into the hole. Greg replaces his ball (correctly) and holes out.
Both players now start the next hole
What is Davids' score for the hole?     [REF: 6M1003]

Playing stroke, David's ball at rest in the general area has area of stance interference by an immovable obstruction.
He has determined the correct relief area and before he drops a ball the Committee immediately stops play due to very dangerous conditions.
Despite knowing this, David compliantly drops a ball into the relief area, then marks and lifts his ball and retreats to safety.
On the resumption of play, David places a different ball, removes the marker and plays that ball.
David gets a total of 2 penalty strokes.       [REF: 6T1045]

In a match, Jill's tee stroke on a hole hits a tree and rebounds back towards her teeing area and comes to rest against one of the tee-markers.
Jill lifts her ball, tees it up elsewhere in the teeing area and plays to the fairway.
Jill gets a 1-stroke penalty.       [REF: 6S1218]