Roland XP-60 Owner's Manual page 152

Deciding which keys to assign Patterns to
When you use RPS only to play Patterns, it does not matter
which keys you assign Patterns to. But if you want to also
play the keyboard normally with the Pattern parameter
(Song/Setup/RPS Setup) OFF, you need to consider a range
of keys to use for RPS.
Because keys to which Patterns are assigned cannot be
checked while playing, it is a good idea to decide on your
key assignments to be sure they're appropriate for the type
of Patterns.
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Chapter 6. Realtime Phrase Sequencing (RPS)
152