In case of
interest (and sorry to be posting so much on
this) the point about abstentions not counting as a vote is standard
practise in all other international organisations.
The definitive
rules of procedure in international relations are those of the UN General
Assembly; these rules date back in their original version to a codification of
customary Rules of Procedure which was made for the Congress of Vienna early
in the 19th century. The Rules have been continually amended and improved ever
since. Robert's Rules of Order and all other recognised rules of procedure are
all derived from the UN General Assembly Rules.
Philip