| Level | Code | Display | Definition |
| 1 | (_Conditional) Abstract | |
Some conditions may be attached to an allowable substitution. An allowable substitution is based on a match to any other attributes that may be specified.
|
| 2 | CONFIRM | Confirm first |
Confirmation with Contact Person prior to making any substitutions has or will occur.
|
| 2 | NOTIFY | Notify first |
Notification to the Contact Person, prior to substitution and through normal institutional procedures, has or will be made.
|
| 1 | NOSUB | No substitution |
Substitution is not permitted.
|
| 1 | UNCOND | Unconditional |
No conditions are required.
|