Aspect-Ratios, Notes
ISO Series 216 / 217 keep an aspect-ratio of √2.
The area of zero-levels generates each serie.
A0 is 1 m², B0 is √2 m², RA0 is 1.05 m², SRA0 is 1.15 m².
ISO Serie C is the geometric mean between A and B formats.
ISO-269/DIN-678 was withdrawn in 2009, but remains usual.
ISO/IEC-7810 also specifies card thickness: 760±80 μm.