| Joseph Rodgers & Sons — stamps and eras (1682 → 1991) | 1682 → at least 1991 | 5 | There are no exact years for Rodgers stamps: what is known are the firm's years of operation and events (1724 — the workshop and the stamp, 1821 — the |
| Country mark (lower bound, NOT a year) | the requirement applies from 1 March 1891 (Tariff Act of 1890, also known as the McKinley Tariff) | 2 | A country mark is only a LOWER BOUND (the item is no earlier than the introduction of the marking) and never a year. For Rodgers the mark ENGLAND is a |
| Grind, spine, scales, etching — era markers of a straight razor | 1700s → mid-1900s | 16 | Shared layer for all straight razors: it does not date precisely, but it cuts off an era. All rows are printed wordings from a shop-page guide review |