Matchplay is different , AFAIK you can putt out of turn but your not entitled to, & ur opponent has the right to make you put it back/replace it and take the putt again when its ur turn ..(Seve , Ryder cup )
Must admit im reading it the same as Gary .. i can walk up and tap it in/ hole out no problem , but
if i lift and mark i lose that right .. BUT
even if i do mark and lif and lose the right , there is no penalty
Apologies if i have that donkey ways around
