Help

To get help about a parameter enter ?. Usually, this will give access to the help-library information for that parameter, for example,

     BOX - Smoothing box size /3,3/ > ?

     BLOCK

       Parameters

         BOX(2) = _INTEGER (Read)
            The x and y sizes (in pixels) of the rectangular box to be
            applied to smooth the image. If only a single value is given,
            then it will be duplicated so that a square filter is used,
            except where the image is one-dimensional, for which the box
            size along the insignificant dimension is set to 1.  The
            values given will be rounded up to positive odd integers,
            if necessary.

     BOX - Smoothing box size /3,3/ >

and then immediately reprompt you for the parameter. There are occasions when information about the parameter is insufficient; you may require to examine the examples or the description of related parameters. This can be achieved by entering ?? to the prompt. You can then delve anywhere in the help information. When you exit the help system you're reprompted for the parameter.