Strange type definition syntax in Golang (name, then type, then string literal)
===

I've been trying to find out how to use mgo (MongoDB driver for Go) and I came across this struct declaration:

    type Something struct {
        Id bson.ObjectId "_id,omitempty"
        Name string
    }

I don't quite understand the sintax of the first element (Id).  I understand that it's being declared as type bson.ObjectId, but what is the string literal doing there?

My question is not about the mgo driver functionality, but about this strange `<name> <type> <string_literal>` syntax.

I couldn't find anything on the Go specs, and I don't know how to google this either.