Making custom requisition field required

Summary

How can i make a custom req field required?

Content

How can I make a custom req field required? I don't see anything in the field edit area that allows me to mark it required.  Also, if there is a way to make it required and once i do that, do I need to go to all open reqs to make it required for them, or do they update automatically?

 

Thanks!

jenn