DMXQueryExtension(3X) - determine if DMX is available
DMXQueryVersion(3X) - determine DMX extension version
DMXSync(3X) - flush protocol requests between Xdmx(1) and back-end X servers
DMXForceWindowCreation(3X) - force immediate back-end window creation
DMXGetScreenCount(3X) - determine number of back-end screens
DMXGetScreenAttributes(3X) - determine back-end screen attributes
DMXChangeScreensAttributes(3X) - change back-end screen attributes
DMXAddScreen(3X) - attach a new back-end screen
DMXRemoveScreen(3X) - detach a back-end screen
DMXGetWindowAttributes(3X) - determine back-end window attributes
DMXGetDesktopAttributes(3X) - determine global bounding box
DMXChangeDesktopAttributes(3X) - change global bounding box
DMXGetInputCount(3X) - determine number of input devices
DMXGetInputAttributes(3X) - determine input device attributes
DMXAddInput(3X) - attach a new backend or console input
DMXRemoveInput(3X) - detach an input
DMXAddBackendInput(3X) - attach a new back-end input
DMXAddConsoleInput(3X) - attach a new console input
Each of these functions is described in its own man page.