The app uses the United States Design Numbering System (USD) devised by PSE (Professional Stamp Experts). For more information about PSE, visit the web site www.psestamp.com.
Sub numbers a, b, c, etc. exist for USD numbers in the case that a USD number has more than one Scott number. Besides a few exceptions, sub numbers exist only for the major Scott numbers; for re-issues, reprints and special printings no sub numbers exist.
Example: For USD number 3 (Franklin 1c; blue imperf) the sub numbers a to h exist which are the Scott numbers 5, 5A, 6, 6b, 7, 8, 8A and 9.
I have asked Amos Press for permission to use the Scott numbering scheme, but unfortunately the response from Amos Press was: 'At the present time we do not license the use of the Scott Catalogue Numbers in apps for mobile devices.'
On the PSE web site a cross reference is available between USD numbers and Scott numbers.
The visibility of sub numbers in the regular stamp list, have list and want list, can be changed by an option on the main menu; initially sub numbers are visible.
Besides a few exceptions, only main numbers have images, sub numbers have not. At the stamp details, gray scale images of main numbers are used for the sub numbers. In the regular stamp list, images of sub numbers are not displayed. In the have and want list, the colour images of main numbers are used for the sub numbers.
Other catalog numbers from the major worldwide catalog publishers can be added manually. The codes used for the catalogs are: SG for Stanley Gibbons, Sc for Scott, Mi for Michel and Yv for Yvert & Tellier.
You can manually add a price, but the catalog does not distinct between the condition of stamps like used, mint, hinged, etc. With kind permission from Brookman Stamps Company, the catalog can import stamp prices of various grades as published in the 2013-2014 price list on the web site www.brookmanstamps.com. After import, for main USD number with sub numbers, the main USD number gets the minimum price of the sub numbers.
Additionally a certificate can be added and viewed in the default web browser if the certificate is from PSE.
The Find by Design option gives an overview with all stamps. Scrolling for the first time in this overview might be slow because of the many images that must be loaded! Scrolling a next time will be faster. For fast scrolling, it is tried to load all images into memory and it depends on the available memory on the device if this is possible. If this is not possible, a message is shown and scrolling in this overview will be slower than usual.
Send me an email if the app is not working properly, if you have any questions or if you want to have specific features added.