Cut sheets of paper meant for printing photographs are commonly sold in these sizes.
Many nominal and effective sizes are specified in international standard ISO 1008 using millimeters only, although most are clearly derived from integer-inch lengths.
In the US, size names are often denoted with a code of the format nR, where the number n represents the length of the shorter edge in inches.
The alternative Super series, denoted SnR, nR Plus or nR+, has an aspect ratio of 3∶2 (or as close as possible) and thus provides a better fit for standard 135 film (35 mm) at sizes of 8 inches or above.
[3] A W suffix indicates sizes with an extended long edge, similar to the American S prefix.