Proposal: Allow the following attributes in a NML Location:

• long is the longitude in WGS84 coordinate system (in decimal degrees)
• lat is the lattitude in WGS84 coordinate system (in decimal degrees)
• alt is the altitude in WGS84 coordinate system (in decimal meters)
• unlocode is the UN/LOCODE location identifier (country code + municipality)
• address is a vCard address
• name is a human-readable string

and if artf6573 is accepted also:
• id is a URI identifier

Note that this proposal does NOT include:
• ISO 3166-1 alpha-2 – two-letter country
• ISO 3166-1 alpha-3 – three-letter country
• ISO 3166-1 numeric – three-digit country codes (numbers, so it's script-independent)
• ISO 3166-2 - provinces and states

The reason for not including these is that in my experience UN/LOCODE covers most use cases, and can easily be related 
to country. If we indeed want to also include countries (not cities) or states/provinces, we can allow ISO 3166-1 alpha-
2 and/or ISO 3166-2 as well. There are probably no problems with such extension.