If Command Extensions are enabled IF changes as follows: IF /I string1 compare-op string2 command IF CMDEXTVERSION number ...

If Command Extensions are enabled IF changes as follows:      IF [/I] string1 compare-op string2 command     IF CMDEXTVERSION number command     IF DEFINED variable command  where compare-op may be one of:      EQU - equal     NEQ - not equal     LSS - less than     LEQ - less than or equal     GTR - greater than     GEQ - greater than or equal  and the /I switch, if specified, says to do case insensitive string compares.  The /I switch can also be used on the string1==string2 form of IF.  These comparisons are generic, in that if both string1 and string2 are both comprised of all numeric digits, then the strings are converted to numbers and a numeric comparison is performed.  The CMDEXTVERSION conditional works just like ERRORLEVEL, except it is comparing against an internal version number associated with the Command Extensions.  The first version is 1.  It will be incremented by one when significant enhancements are added to the Command Extensions. CMDEXTVERSION conditional is never true when Command Extensions are disabled.  The DEFINED conditional works just like EXISTS except it takes an environment variable name and returns true if the environment variable is defined.