Product SiteDocumentation Site Out and In UGens

The "Out" UGen is discussed in Section, “"Out" UGen”. What it does is take a signal and route it to the specified bus number. The "In" UGen performs a similar action: take a signal from a bus number, and make it available for use.
This is the syntax to use for the Out UGen:, audioRateUGen);

or, controlRateUGen);

The UGen enclosed here should not be enclosed in a Function. If the UGen provides multi-channel output, "Out" will automatically route the lowest channel to the specified bus number, the next channel to the next highest bus number, and so on. This way, you can achieve stereo output with one "Out" UGen.
This is the syntax to use for the In UGen:, numberOfChannels);

or, numberOfChannels);

Whereas "Out" automatically outputs the right number of channels based on how many you provide, "In" requires that you specify how many channels you want it to fetch for you.
When created with this form, both of these UGens automatically connect to the default server, stored in the single-letter "s" variable by the interpreter.