Groups of Data Files

If a group expression is used to specify a list of input data files, then file names may be specified which contain wild card characters (``*'' and ``?''). These will be expanded into a list of explicit file names before returning the group to the application. Note, group expressions containing wild-cards must be enclosed in quotes if they are supplied on the command line (this prevents the shell from expanding the wild-cards itself).

If the final character in a group expression is a colon (:), then a list of the data files represented by the group expression (minus the colon) is displayed, but no data files are actually added to the group of files to be processed. The user is then re-prompted for another group expression. Note, this facility only applies to group expressions representing existing data files, not data files which are to be created by the application.

If an HDS container file¹¹ is supplied which contains two or more NDF structures, then each NDF within the container file is processed as a separate image. NDFs which are contained within an extension of another NDF are not included.

If a group of output NDFs are created by modification of a group of input NDFs (i.e. if the supplied string includes an asterisk), then the structure of each output container file will be copied from the corresponding input container file. For instance, if the container file o66_int.sdf contains 16 NDFs in components I1 to I16, then specifying ``o66_int'' when asked for a group of input images will result in all 16 NDFs being used. If the corresponding output images are specified using the string ``*_A'' then a single output file named o66_int_A.sdf will be created. The structure of this file will be copied from the input file, and will therefore contain the 16 output NDFs in components I1 to I16.