XcupQueryVersion man page
XcupQueryVersion — Returns TOG-CUP protocol version supported by the X server
cc [ flag ... ] file ... -lXext [ library ... ] #include <X11/extensions/Xcup.h> Status XcupQueryVersion(Display *display, int *major_version_return, int *minor_version_return);
Specifies the connection to the X server
Returns the major version supported by the server
Returns the minor version supported by the server
XcupQueryVersion sets major_version_return and minor_version_return to the major and minor TOG-CUP protocol version supported by the server. If the TOG-CUP library is compatible with the version returned by the server, it returns nonzero. If the server does not support the TOG-CUP extension, or if there was an error during communications with the server, or if the server and library protocol versions are incompatible, it returns zero. No other Xcup functions may be called before this function. If a client violates this rule, the effects of all subsequent Xcup calls that it makes are undefined.
To get the list of reserved colormap entries, use XcupGetReservedColormapEntries.
To allocate one or more read-only color cells with RGB values, use XcupStoreColors.
Colormap Utilization Policy and Extension