> Programming Considerations > Managing Input and Output > Controlling Message Channels

In both the Interactive Optimizer and the Callable Library, there are message channels that enable you to direct output from your application as you prefer. In the Interactive Optimizer, these channels are defined by the command set output channel with its options as listed in Table 6.2. In the Callable Library, there are routines for managing message channels, in addition to parameters that you can set. The following sections offer more details about these ideas: