55.3 Optional nodes
Individual nodes can be marked as optional in a definition by setting the minimum
value in the repeat or occurrences section to "0",
see repeat/occurrences.
To avoid having to account for certain nodes in definitions at all, specify them
in definitions with the procedure name qfs.ignore.event
(alternative: qfs.event.ignore).
As the first step in converting node sequences, these nodes are removed entirely
from the sequence. In the second step, the remaining definitions are applied to
the remaining node sequence.
This approach is useful for MOVED mouse events on menu items, for
example. PRESSED or RELEASED keyboard events that are
recorded in addition to the actual keyboard event are also sometimes best filtered
out in the first step.