Base roster- the turns for each member of staff to work and cover all diagrams within a depot.
7 day sheet- comes from Rosters and shows turns that will be worked 7 days in advance. This reflects actual staff availability- sickness, floating leave, allocated leave, rules days etc. Folks will look at the 7day, see what turns are uncovered and may put in for RDW at this point, if they haven't already done so. Can be allocated a turn, from spare, at this point.
48hr sheet- the latest information on staff availability. Once 48hr sheet is posted that's what you're working and can't be changed without mutual agreement.
I can get moved +/- 3hrs if I'm allocated a turn 7days in advance, +/- 2 1/2 after this but before the 48hrs.
Sometimes, I can be allocated a turn on the 7day, then someone will volunteer for Rest Day Working. If this happens then the 48hr sheet will show this. I'll remain booking on at the turn start time, but will be spare while the RDW will work the turn. This depends on local union agreements but generally rest day work volunteers will be used before spares.
Can be asked to cover an uncovered job that doesn't fit their spare hours, with less than two days notice with mutual agreement.
Always remember that you need 12clear hours minimum between shift ends and starts. Rosters want to run trains and won't always be aware of your turns, so you might agree to a later finish and then find you've not got enough rest between the next shift. Also, depots don't generally like you switching from late to early turns, and vice versa, within a working week. Don't ever be pressured into moving if it doesn't suit you and if trains have to be cancelled because there's no crew to run them, then so be it. That's not your fault or responsibility. Someone somewhere will do some jiggery pokery and work it out. Of course, you can always see if there's a sweetner to incentivise you to move at late notice, but that's up to you.
Use spare turns to do admin, like updating Sectional Appendices. Some depots do 'cut outs' where you do part of a long or boring turn so someone gets a better break or an early finish. If you've got long term sick, or vacancies, on your side of the link, you might not get a spare turn for months.
Additionally, if you sign the same routes and traction as another depot, you may be spare on the day, but find you've got whole or part of a job from the other depot, depending on cover agreements. If so, do the job and go home.