How to tag motor service stations and rest places on motorway?

I want to map some motor service stations and rest places on a motorway.
It isn’t clear to me what type the streets should be.
They could be tagged “motorway_link” or “service”. I have seen both on OSM.
The wiki doesn’t give much detail about this.

IMHO “motorway_link” makes the most sence, since it is part of the highway.
At the same time, people are allowed to cross the street by foot.

Service doesn’t seem to be correct. I understood that it is a road that connect a motor service stations to the normal roads, e.g. for supply. And that it isn’t connected to the motorway (it doesn’t provide access).

What is the correct way?
Is it a mixture?:
The ramps as “motorway_link” and the roads where parking and crossing the street by foot is allowed as “service”?

Please advice. The wiki should be changed accordingly.

As far as I can tell from http://wiki.openstreetmap.org/index.php/Map_Features your mixture suggestion is correct. But I’m no expert!

Personally i wouldn’t label every road in the car park, but use a loop way to define edges of parking, and mark only significant routes through the service area.

I would say a mixture as well (motorway_link where highway rules apply, service where providing access to parking and/or fuel).