                    IF - Conditional command execution
    
    SYNTAX:

        if [not] <string1> == <string2> <commands> [! else ! <commands>]
        
           or
        
        if [not] exist <filename> <commands> [! else ! <commands>]

           or

        if [not] os <os-string> <commands> [! else ! <commands>]

           or

        if [not] term <terminal-type> <commands> [! else ! <commands>]

           or, if Multibus II system
           
        if [not] slot <slot-num> <commands> [! else ! <commands>]

           or
           
        if [not] type <board-type> <commands> [! else ! <commands>]

                    
    PARAMETERS:

        string1         A string of characters. Strings may only contain
                        separators (commas, semicolons, equal signs, spaces
                        or tabs) if the entire string is surrounded by quote
                        (") signs.
        
        string2         A second string of characters.
        
        filename        A pathname for a file. While this pathname may be file
                        ambiguous, it must not be directory ambiguous.

        os-string       The name of the operating system to be checked for.
                        Possible names are "iRMX I", "iRMX II" and "iRMX III".

        terminal-type   The type of terminal in use. Supported types and
                        current type are as specified in the :CONFIG:TERMCAP
                        and :CONFIG:TERMINALS files.

        slot-num        A Multibus II slot number. Acceptable values are in
                        the range 0 - 19.

        board-type      The type of board on which the command is executing.
                        Examples of valid types are "386/258", "486/133SE"
                        and "386/120".

        commands        One or more commands, separated by exclamation marks
                        ('!'), which are to be executed.

    DESCRIPTION:

        The IF command allows for the conditional execution of command(s).
        When the condition is true, IF executes all command(s) preceding the
        "else" command; otherwise, it executes all command(s) following the
        "else" command. If the keyword NOT is specified, the reverse is the
        case.
        
        The conditions are described as follows:
        
            EXIST filename      True if, and only if, the designated file(s)
                                exist.
            
            string1 == string2  True if, and only if, the two strings are
                                identical (in a batch file, this would be
                                after parameter substitution). Note that a
                                case-insensitive comparison is made.

            OS os-string        True if, and only if, the running operating
                                system has name <os-string>. <os-string> must
                                be one of the following: "iRMX I", "iRMX II"
                                or "iRMX III". Note that case is not important.

            TERM terminal-type  True if, and only if, the current terminal
                                type has name <terminal-type>.
                                
            SLOT slot-num       True if, and only if, the command if being
                                executed by the processor in Multibus II card
                                slot <slot-num>.

    EXAMPLES:
        
        1. A command to produce a message if files with a certain extension
           exist:
        
            if exist /user/super/*.c echo C source files exist
      
        2. An example submit file to do a compile, a bind, a map generation
           or all three for a program:

            if %0 == compile ic286 ...
            if %0 == bind bnd286 ...
            if %0 == map map286 ...
            if %0 == all ic286 ... !bnd286 ... !map286 ...
