Mapper since: December 14, 2008
I live in Germany.
1. OSM is an international project with english language ==> keys/tags should be english and have identical meaning all over the planet.
2. Avoid private keys/tags without wiki and check for available existing ones.
3. GPS precision in elevation is never below 1 mm (typically good GPS gets 10 meters if you are lucky). ==> ele = 123.456789 (m) does not make sence..
4. Avoid empty keys “”, and keys or values containing invisible chars (e.g. 0x7F often seen).