PathExt

PathExt = Yes | NO:  Determines whether CMD.EXE will use the PATHEXT 
environment variable.  If set to No (the default), the PATHEXT variable is 
ignored.  If set to Yes, the PATHEXT variable will be used to determine 
extensions to look for when searching the PATH for an executable file. 
 For details, see the PATHEXT variable and the PATH command. 

CAUTION:  If you set PathExt = Yes in CMD.INI and then fail to set the 
PATHEXT variable, path searches will fail as there will be no extensions 
for which to search! 

PATHEXT is supported for compatibility reasons but should not generally be 
used as a substitute for the more flexible executable extensions feature.