README for XFree86 on OS/2 : Adding Variables to CONFIG.SYS . ... ETC . Set to an ETC directory. Normally, this is already set to the ETC directory of the TCP/IP code, such as SET ETC=C:\TCPIP\ETC For Warp 4 and later, this may point to the \MPTN\ directory. ... Normally you will set this variable to the same value as the HOSTNAME variable and simply add a :0.0 after it, such as SET DISPLAY=myhost:0.0 Read the X11 man page on the exact meaning of these postfixes and other options. ...