Standard Library procedure that lets you implement a “hit any key to
continue” function.

None.

Mesg—Alerts the user that the procedure is momentarily stopped. If set to 1 (the default), the following message is printed on the display screen:

Mesg may also be set to an arbitrary string.

HAK waits for keyboard input, clears the typeahead buffer, and allows the application to continue. It is used primarily to stop a procedure momentarily—for example, to allow the user to read an explanation screen or view a temporary plot.

a = INDGEN(100)

PLOT, a

HAK

; PV-WAVE halts execution until a key stroke,

; without printing a message

PLOT, a + 100

t = 'When ready, press a key...'

HAK, Mesg=t

; PV-WAVE prints: When ready, press a key...

; and then waits for a key stroke 

WAIT