Swap variable names: rename (v1 v2) (v2 v1)
Lowercase (or uppercase, or propercase) groups of variable names: rename V1 V2, lower or rename *, lower
Add suffix _old to variables v1, v2, … for one or more digits: rename v# =_old
Remove suffix _old from all variables ending in _old: rename *_old *
The meaning of each specifier:
