[OSM-newbies] Bus stop IDs

[Serge Wroclawski]

This page: http://wiki.openstreetmap.org/wiki/Tag:highway%3Dbus_stop

Talks about "Asset reference numbers". Is this the equivilant of bus stop IDs?

WMTA (the Washington [DC] Metro Transit Authority) has bus stop IDs on
most (all?) bus stops so that you can use a service they provide to
determine arrival times of buses.

I'd like to add this as a tag to the stop in OSM, but am not sure what
the right tag is.

Thanks,

- Serge