SF: play.c
SN: list of commands
---
-N: play
-D: Start or resume playing.
-U: play [<num>]
-H: Without <num>, starts playing at the current position. Otherwise, the
-H: corresponding file is loaded and playback is started.
----
-N: pause
-D: Stop playing.
-U: pause
-H: When paused, it is still possible to jump around in the file via the jmp and ff
-H: comands.
----
N: tasks
D: Print list of active tasks.
U: tasks