These routines get and set the CMW label of a window. Refer to the XTSOLgetResLabel(3) and XTSOLsetResLabel(3) man pages.
Status XTSOLgetResLabel(Display *display, XID object, ResourceType resourceFlag, bclabel_t *cmwlabel); void XTSOLsetResLabel(Display *display, XID object, ResourceType resourceFlag, bclabel_t *cmwLabel, enum setting_flag labelFlag);