The Geolocation API must provide location data in terms of a pair of latitude and longitude coordinates.

I am not a GIS expert, but my GIS friends constantly remind me that there
is no such thing as latitude and longitude.  Such numbers are dependent on
the geodetic system used.

Futher, the draft arbitarily uses wgs84 for altitude, so it may be that
this is also intended to be used for latitude and longitude.  This would
not be acceptable in Australia, for example.  In New South Wales, and
Australian state, all candastre (land) data is supplied in a couple of
Australian standard.  So wgs84 locations would not correctly show which
street you were standing.

I suggest the standard needs to require the inclusion of the geodetic
system.  The standard may need to propose a list of supported geodetic
systems.