Just received an RFP (request for proposal) for a semi-custom terminal from a subcontractor for the US Army. The specs are entirely metric, with one exception: character height on the display is specified at 0.15". All other specs, including mechanical, keypad sizes, temperatures, sealing pressures, etc. are metric.
I can't explain the 0.15" (3.81 mm) -- it is not any kind of standard for character displays. The ubiquitous 4x20 LCD modules used in these devices nearly universally use characters that are 4.75 mm high. I believe the specification is from the Army, and not a metric rendition created by the subcontractor. Jim Elwell
