This command is used to add a viewport to a moan channel. Subsequent programs ran on the moan channel will then affect it.
It is possible to add a viewport to multiple channels. When this is done, the overall effect on the viewport will be a composite of the individual channels.
A viewport can be added to the same channel multiple times, this will cause it to be doubly affected by the channel, ie where a move command would move it x pixels, it will instead move it 2*x pixels.
canvasId is the number of the canvas that the viewport is viewport is viewing, it will be added to the channel.See also Add Sprite To Channel, Remove Sprite From Channel, Remove Viewport From Channel.
channelId is the number of the moan channel to add the viewport to.