DPMSGetVersion - returns the version of the DPMS extension implemented by the X
  server
cc [ flag ... ] file ... -lXext [ library ... ]
#include <X11/extensions/dpms.h>
Status DPMSGetVersion
(
      Display *display,
      int *major_version,
      int *minor_version
);
  - display
- Specifies the connection to the X server
- major_version
- Specifies the return location for the extension major version
- minor_version
- Specifies the return location for the extension minor version
The DPMSGetVersion function returns the version of the Display Power
  Management Signaling (DPMS) extension implemented by the X server. It returns
  a major and minor version number. The major version number will be incremented
  for protocol incompatible changes, and the minor version number will be
  incremented for small, upward compatible changes.
  - TRUE
- The DPMSGetVersion function returns TRUE when the extension is
      supported and values are returned.
- FALSE
- The DPMSGetVersion function returns FALSE when the extension is not
      supported.
DPMSCapable(3), DPMSQueryExtension(3)