Sending note-off messages to 'busy' poly~ instances

    Jun 14 2011 | 4:22 pm
    Hey I'm currently trying to get my head around using the [poly~] object. I understand that if you send a [prepend note] or [prepend midinote] message (whats the difference between these two messages by the way?) to the [poly~] object it searches for a 'free' instance, I understand that sending a non-zero value to the [thispoly~] object sets the instance to 'busy', and sending a zero value frees the instance again.
    I've been looking at the tutorial examples and I understand that the instances are free used the [line~] object controlling the note amplitude. However I'm trying to use the [poly~] object for sounds that don't decay; there is no [line~] object controlling the amplitude, and the note is turned off by sending a note-off/zero value. However you can't send any data to a 'busy' instance, so how would I go about sending the correct instance a note-off/zero message? Is it possible with [poly~]?