Various important examples which come up on Shabbos in conjunction with the halachas of perfuming or putting in a nice smell into an item;
Is One Allowed to Remove Fruits from a Branch That Was Broken Off Before Shabbos? Removing Grapes from the Stem on Shabbos;
(Temporary Ohel) Putting up a curtain between men and women. Making a wall of a Sukkah;