Of the basic PeopleTools tables, the USEEDIT field of the record field properties (PSRECFIELD) is perhaps the most intruiging. The USEEDIT field is a 32-bit integer field. For some reason (is it for maximizing space? is it forward-thinking? to eliminate the need to add fields on future attributes?), PeopleSoft crammed a bunch of field properties into this single field. PeopleSoft did this by assigning a property to each bit of the field value.
For example: if the value of USEEDIT is 257, its binary representation is 0000000100000001. As you can see, the rightmost 1st bit and the 9th bit are turned on. The 1st bit represents the Key attribute, whereas the 9th bit represents the Required attribute. This means that a USEEDIT value of 257 represents a field which is both a Key and is Required.