What is the meaning of a PM account in Opera
PM Account is refereed to ‘Posting Master’ or ‘Pay Master’ dummy rooms. Such Dummy or Pseudo rooms are normally used to to post Group Related charges or Group invoice.
Other functions of PM rooms are posting miscellaneous charges for chance sales or passer by guest, interface posting charges for Credit Card, Cash settlements etc.
Moving unsettled rooms as bills on hold to the PM account etc.
I second what @thinkhotelier said and also ‘PM - Posting master’ rooms are not actual rooms so the hotel can create as many such rooms without bothering about the license fees.
Such dummy rooms can be also used to post Banquet related charges or billing in case your hotel does not have a Sales and Catering module.