.tr

.tr 

ab

Translate character a (first of a pair) to b (second of pair).

Example

Produce uppercase, and later restore. Useful for title macros:

.tr aAbBcCdDeEfFgGhHiIjJkKlLmM     
Et cetera

.tr aabbccddeeffgghhiijjkkllmm     
Et cetera