| Fold symbol. Never use for size. |
Size letter. Never use for fold. |
Outside height. In centimeters. |
|---|---|---|
| 48º | Fe | Up to 10 |
| 32º | Tt | 10 – 12.5 |
| 24º | T | 12.5 – 15 |
| 16º | S | 15 – 17.5 |
| 12º | D | 17.5 – 20 |
| 8º | O | 20 – 25 |
| 4º | Q | 25 – 30 |
| fº | F | 30 – 35 |
| F⁴ | 35 – 40 | |
| F⁵ | 40 – 50 |
Prefix nar. if width is less than ⅗ height.
Prefix sq. if width is more than ¾ height.
Prefix ob. if width is more than height.
For all books over 35cm high the superior figures show in which 10cm of height the book falls, e. g., F⁸ is between 70 and 80cm high.
Give all sizes in cm (for greater accuracy adding decimals), leaving the old symbols and names, 8º and Octavo to indicate fold only. Give height first, followed by h, or by × and width, e. g., 23h or 23 × 14. 23h means between 22 and 23, i. e., in 23d cm. All measures are taken outside the cover. Width is from hinge to edge not including the round. To measure paper or letter-press, prefix p(aper) or t(ype) to figures, including in type neither folio nor signature lines.