“ The four leniencies are:
taking wood from any place exempt from washing - Normally people are required to wash their hands both before and after a meal. Soldiers were exempt. The gemara explains that this exemption was only for the washing before the meal, and that the washing afterwards was still incumbent upon them. demai - Demai is produce which is only questionably tithed. (The person isn't sure if it has been tithed or not) . Usually a person is forbidden to eat it until they remove their own tithe in order to ensure it has been tithed. ”