Search for rail stations by operator's codes

Many rail operators have a system of codes for identifying their stations - e.g. DB, National Rail in the UK, Amtrak. Many of these have been added to OSM data, typically tagged as "railway:ref" (though National Rail codes are "ref:crs"). It would be helpful if these codes could be used when searching for stations, for both speed and ease of identification. "KGX" is both unique, and faster to type than "London King's Cross".