Motif widgets support none, some, or all of the following data transfer mechanisms:
The Uniform Transfer Method (UTM) is not the fifth mechanism. Rather, UTM unifies and simplifies the way in which the four mechanisms are implemented. For example, consider an application that uses UTM to implement primary transfer. To add support for a UTM clipboard transfer, the application programmer need only write a little extra code. That is because UTM makes it easy for the different data transfer mechanisms to share code.
As of Motif Release 2.0, all widgets and applications that implement data transfer should use UTM for that implementation. As of Motif Release 2.0, the Motif toolkit implements data transfer exclusively through UTM.