- doc: /* Return the version numbers of the X server of display TERMINAL.
-The value is a list of three integers: the major and minor
-version numbers of the X Protocol in use, and the distributor-specific release
-number. See also the function `x-server-vendor'.
+ doc: /* Return the version numbers of the GUI software on TERMINAL.
+The value is a list of three integers specifying the version of the GUI
+software in use.
+
+For GNU and Unix system, the first 2 numbers are the version of the X
+Protocol used on TERMINAL and the 3rd number is the distributor-specific
+release number. For MS-Windows, the 3 numbers report the version and
+the build number of the OS.
+
+See also the function `x-server-vendor'.