Add blocked piece size to 'predefined' size list

In GSplit there is a reference to being able to add your own blocked sizes to the ‘predefined’ list, but I couldn’t find how to do that in either the help file or this forum. I’ve found that for the purposes of storing ISO images larger than a DVD, I can break them into four pieces at 1,120 MB ea and lose less than 10 MB of space. I’d like to add this block size to my ‘predefined’ list.
Great program by the way. Thanks.

This should help you:
http://www.gdgsoft.com/gsplit/help/TechnicalDoc.htm#P3

Oops, I did a search for ‘predefined’ that did give this section as a result, as I mentioned, but since this section is mostly about command-line switches and batch files, I assumed, as I believe most people would, that it didn’t refer to changing the options in the GUI of the program. I apologize if my reasoning seemed in error, but I believe that command-line switches and batch files are generally for programmer types with ‘old-school’ knowledge of DOS, but editing a simple text file to change start-up preferences, registry entries and the like is much more common nowadays and such options don’t generally change the menus in the GUI.
Thanks for your quick response. I love this program; how better to make it more personal than to add my own options.