Drift modifiers input is not documented.

But obviously aren't to be deleted #1551 #1531

**To Reproduce**
Create bug with drift modifiers, try and figure out how they are actually supposed to work and what legal input is.

**Expected behavior**
A clear and concise description of what you expected to happen.

**System:**
- system name [e.g. fusiont5, summit]
- modules loaded [e.g. output of `module list`]
- other systems where this is reproducible [e.g. "my laptop", "none"]

**Additional context**
Add any other context about the problem here.