Every category that you specify must match an entry of the RST directory in order to be displayed. If only the first field of a range is specified, then a directory entry must match that value just like it would for the categories with only one entry field.
All string comparisons are case-insensitive.
When an entry string is not part of a range, it matches a directory entry if it is found anywhere in the directory entry string. See the search instructions for more complete details. BIG thanks are due John Walker for writing the program that handles all of the RST data.