==== <code>ON SQ(x) GOSUB ln x1, x2, x3, x4, ...</code> ====
:ON SQ(x) can trigger an interrupt when e.g. a space or free channel in queue.
:Using that command is a one way interrupt trigger and shouldn't be mixed with EVERY or AFTER commands.
:See also the SQ(x) command for more details.
==== <code>OPENIN "datafile"</code> ====