Hello Greg,
Welcome to the board. Not to sound snide, but the awnser to your question can be found if you delve deeper into this forum and look at other topics which are similar to yours. Myself and others who work in the industry have spelled it out quite well.
In short, on the UP, if you work a turn, say a pool job where you travel from your home terminal to an outlying crew change point, you are generally gone from home anywhere from 24-38 hours. There are no set days off, unless you can work a local or yard job. The extra board is also 24/7/365, again no days off. If you wish to have a day off, you will have to call cms (crew mgt.) and let them know you are sick.
Brgds