| Number Prefix or Suffix (as noted) | Category | Catalog or System (country) |
|---|
| Stamps and other postal items |
|---|
| none | regular postage | Scott (USA) |
| B (prefix) | semi-postal | Scott (USA) |
| C | air post | Scott (USA) |
| CD | common design | Scott (USA) |
| CP | commemorative panel (un-canceled) | Scott (USA) |
| D | pneumatic | Scott (USA) |
| F | registration | Scott (USA) |
| J | postage due | Scott (USA) |
| L | dependencies/territories | Scott (USA) |
| MH | Machin Head (or Machin) definitive | Scott (USA) |
| NB | occupation semi-postal | Scott (USA) |
| NC | occupation air post | Scott (USA) |
| O | official | Scott (USA) |
| OY | life insurance | Scott (USA) |
| Q | parcel post | Scott (USA) |
| R | revenue | Scott (USA) |
| RA | postal tax | Scott (USA) |
| RAC | postal tax air post | Scott (USA) |
| RAJ | postal tax due | Scott (USA) |
| SC | souvenir card | Scott (USA) |
| SP | (earlier) stamp poster or (later) souvenir page (with FD cancel) | Scott (USA) |
| U | stamped envelope | Scott (USA) |
| UC | aerogramme | Scott (USA) |
| UX | postal card | Scott (USA) |
| UXC | air postal card | Scott (USA) |
| Z | prefecture | Scott (USA) |
|
|
| i (prefix) | imperforate version | this site's designation (for use with Scott numbers mainly, but not exclusively) |
|
|
| A (suffix) | perforated | Michel (Germany) |
| B (suffix) | imperforate | Michel (Germany) |
| BL | block/sheet | Michel (Germany) |
| MH | booklet | Michel (Germany) |
| Mi | regular postage | Michel (Germany) |
|
|
| m | | Minkus (USA, discontinued worldwide in 1974, in the USA in 2004) |
|
|
| CNEP | Chambre des Négociants et Experts en Philatélie (Chamber of Dealers and Experts in Philately) | Yvert (France) |
| BL1 | block/sheet | Yvert (France) |
| PA | air post | Yvert (France) |
| Yv | regular postage | Yvert (France) |
|
|
| WB | regular postage | Weebau (Belgium) |
| Coins |
|---|
| KM | | Krause and Mishler (USA) |
| Y | | Yoeman (USA) |
| Banknotes |
|---|
| P | | Pick (USA) |
