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