rest duration 

Inserts a rest in a sequence of notes. The duration is in tenths of a second, and has a maximum of 255. 

Example: 

note 60 5 note 62 5 note 64 5 
rest 5 note 60 5 note 62 5

Or, as a procedure:

to song
note 60 5 
note 62 5 
note 64 5 
rest 5 
note 60 5 
note 62 5
end