The TUIO protocol provides a general and versatile communication interface between controller interfaces and applications. The TUIO In DAT can receive TUIO messages from other applications on the network and parse them into columns. The protocol is encoded using the OSC format which also allows TouchDesigner to get raw message data from the specification using the OSC In CHOP or OSC In DAT.
Details about the TUIO specification can be found at www.tuio.org
The TUIO specification includes profiles for 2D, 3D, and custom interactive surfaces.
For example applications, see Nuigroup's Community Core Vision (CCV) vision-based tracking software and a list of other TUIO software implementations here.