| Name | 
Type | 
Opt | 
Description | 
| MIDI-port (a through z) | 
symbol | 
opt | 
 Specifies the port from which to receive incoming MIDI messages. If there is no argument, polyin receives from all channels on all ports.  | 
| (MIDI name) | 
symbol | 
opt | 
 The name of a MIDI input device may be used as the first argument to specify the port.  | 
| MIDI-port (a through z) and channel-number (int) | 
list | 
 | 
 A letter and number combination (separated by a space) indicates a port and a specific MIDI channel on which to receive polyphonic key pressure messages. Channel numbers greater than 16 will be wrapped around to stay within the 1-16 range.  | 
| channel-number | 
int | 
 | 
 A number alone can be used in place of a letter and number combination. The exact meaning of the channel number argument depends on the channel offset specified for each port in the MIDI Setup dialog.  |