I know that PNG doesn't support EXIF metadata (see these questions) but it does support its own format of Chunks including text as a "name=value" pair. However, I can't find any standard for the naming of text apart from these basic keywords.
There's a reference in the second question to this failed standard from 2000 which defines fields like:
- GPSAltitude
- GPSAltitudeRef
- GPSInfo
- GPSLatitude
- GPSLatitudeRef
- GPSLongitude
- GPSLongitudeRef
- GPSMapDatum
- GPSVersionID
and they seem to be used in this discussion. Should I just use these or is there an official standard I can use?
