just got hired as per diem.. how does it work?

So recently I just got an offer to do a nursing internship partime.

and i just got a job offer as per diem nurse at a local hospital. (new grad yippy!)

This is a sillly questions, but i'm unsure of how per diem actually works. The hospital wasnt specific what hours they wanted me to do as per diem, i didn't sign anything, and they said all shifts are available for per diem. (they are planning to offer me a salary quote next week).

if i signed on to be a per diem nurse.. does that mean if I tell them i'm available only on Tues, Weds, Thurs, they can call me any hour of the day? .. or they can only call only for Nocs if i choose noc shift. The thing is, i got the internship after my job interview, so now my availability has changed. the internship has solid hours already. unsure of how i should juggle both internship and per diem job.
Different hospitals handle "per diem" different ways, so your best bet is to ask your employer and be v. clear what you're agreeing to by taking the position. Some places have a rule that, if they call you and you turn them down x number of times, you're dropped from the per diem pool/list. Some have rules about how many holidays or weekends you have to work to stay employed. The possibilities are pretty wide, so make sure you know what your employer requires or expects.

And get EVERYTHING in writing. From BOTH places.Generally, if you are per diem, they will ask you for your availability for a particular time period, and then plug you into the schedule as needed. Pay close attention to the how often you must work, how often you can say no, etc.

Deffintaly ask them and get it in writting. I work per diem/registry as a CNA and I have to be available to work 3 12hour shifts per month with on of them being a weekend shift, and I can say I prefer 7a, 11a, 3pm, 7pm start times, but I am the first one to be floated and the first one to be called off

thank you guys for the replies it is definitely helpful