This applies to the documentation specifically, but the title is already exactly the character limit
While the action description within VoiceAttack itself states
This is used simply to keep unrecognized phrases from showing up in the log
The documentation states
'Ignore an Unrecognized Word or Phrase'
This is tricky to explain. This basically just discards the recognized command and does not report it in the recognition log. I added this feature because sometimes the speech recognition engine picks up background noise and breathing as commands.
You will see entries in the recognition log like: "Unrecognized Command: 'if if if'".
Chances are, you will see things like this, too. Just add the irritating phrase as a command and select this option all by itself in the action sequence.
(Bold emphasis mine)
While the original intent seems to be creating "dummy" commands that do nothing but hide erroneously recognized phrases from the log, the action can also serve to hide any given command from the log.
However, because the help document implies(or at least can be inferred from) the command won't actually execute if it contains this action, that alternate usage is less likely to be intuited.
Unless of course the action actually is supposed to stop the command from executing entirely, in which case I suppose this is a feature request instead
EDIT: Checked in v1.7.2.21, behavior remains, documentation unchanged.
EDIT#2: Checked in v1.7.7.5, both remain unchanged.