ISO 9241 is an international standard covering health and safety in the work place for users of visual display terminals. Part 3 of this standard covers clarity and legibility of text displayed on computer screens; it places requirements on minimum sizes and luminance contrast. The presence of the FM_SEL_ISO9241_TESTED flag in the FONTMETRICS structure indicates that the font has been tested for ISO compliance.
Note: While the fonts were primarily tested for meeting the ISO standard, they have also been designed to meet the German standard DIN 66 234. Where the two standards differ, the fonts have been designed to meet the stricter requirement.
The FM_ISO_xxx flags indicate the results of the test on the three IBM displays that conform to the standard. These are the IBM 9515, 9517, and 9518 color displays at the supported resolutions of 640 x 480 and 1024 x 768. To determine whether a non-IBM display complies with ISO 9241, contact the manufacturer. The current display type can be established using VioGetConfig.
In order for applications to meet the standard, they have to ensure that they use only fonts that have been tested and passed. You can determine this by examining the new FM_SEL_ISO9241_TESTED flag in the fsSelection parameter in the FONTMETRICS structure, the FM_ISO_xxx flags and the sXDeviceRes and sYDeviceRes fields in the structure.
See Fonts Supplied with the OS/2 Operating System for the table describing ISO 9241 compliant fonts.