-<li>MESA_RGB_VISUAL - specifies the X visual and depth for RGB mode (X only)
-<li>MESA_CI_VISUAL - specifies the X visual and depth for CI mode (X only)
-<li>MESA_BACK_BUFFER - specifies how to implement the back color buffer (X only)
-<li>MESA_GAMMA - gamma correction coefficients (X only)
-<li>MESA_XSYNC - enable synchronous X behavior (for X debugging only)
-<li>MESA_GLX_FORCE_CI - if set, force GLX to treak 8bpp visuals as CI visuals
+<li>MESA_RGB_VISUAL - specifies the X visual and depth for RGB mode
+<li>MESA_CI_VISUAL - specifies the X visual and depth for CI mode
+<li>MESA_BACK_BUFFER - specifies how to implement the back color buffer,
+ either "pixmap" or "ximage"
+<li>MESA_GAMMA - gamma correction coefficients for red, green, blue channels
+<li>MESA_XSYNC - enable synchronous X behavior (for debugging only)
+<li>MESA_GLX_FORCE_CI - if set, force GLX to treat 8bpp visuals as CI visuals