Basic idea. In deciding which micro-variations to list and which to ignore, I try to walk the middle ground between "lumpers" and "splitters." My goal is to list variations only when substantial numbers of collectors prove they care by routinely and predictably paying more.

The hard reality. Certain factors govern my decisions about inclusions and exclusions.

• I want to keep the size of the printed catalog manageable.
• Collectors rarely pay premiums for micro-variations, regardless of scarcity.

In general, I create varieties based upon the appearance of certificates when they left printing and engraving companies. With few exceptions, I do not create varieties based upon markings made upon certificates after that time. I do, however, make separate listings and price estimates for variations that routinely affect values of certificates such as:

• states of issuance (issued vs unissued)
• states of cancellation (cancelled vs uncancelled)
• autographs by notable celebrities

I do NOT create separate listings for:

• autographs from minor celebrities (please see autograph criteria for an in-depth discussion of minor celebrities)
• autographs from ordinary company officers
• certificates issued to celebrities but not signed by them (also included in the discussion of autograph criteria)
• variations in types or degrees of cancellations
• variations in trust company or clearing house names
• variations in designs of backs of certificates
• handwritten or overprinted share values
• minor size differences
• minor color variations

I constantly strive to control the scope of my project and the size of the resulting catalog. For instance, if I recorded and tracked every boldly overprinted share value on all twenty-two varieties of Pennsylvania Railroad stock certificates, I might increase the number of possible listings by several thousand. Autographs from minor celebrities or company officers could add several thousand more. Cancellation variations could conceivably add still more thousands. Yet, such a massively increased number of listings would be essentially pointless because few if any collectors currently pay more for such variations.