Expanding place names

What is the policy on permanent abbreviations in place names? Some places are named St Paul, that has always been their name, never Saint Paul, but someone has been unabbreviating it to the latter for some reason. This doesn’t make sense to me. Are there any guidelines on this or could it just be that someone has taken it upon themselves to change it?

We usually always use the long Name.
Read http://wiki.openstreetmap.org/wiki/Name and it should be clear why.

The data we enter can be used by many different applications.“st” can be interpreted as “street” or “saint”. It is the responsibility of the application to convert the full name to its short form but the conversion is not always possible in the other way.

Entering the full version is recommended worldwide, see this wiki page for instance:

Of course this doesn’t eliminate all ambiguities, such as North Boulevard: is it a boulevard named North, or the part of Boulevard north of the zero line? The benefits seem to outweigh the costs though.

However, if something’s always known as a short form - such as Rhode Island vs. Rhode Island and Providence Plantations, official_name is the way to show the long name. I don’t know if this would apply to abbreviations - how about something like Attleboro vs. Attleborough, to get away from the more common abbrevations?

Okay, so it seems that it would be correct to allow the abbreviation if that is the official name (like St Albans) but not if the abbreviation just happens to be on signs.

There is still a part of me that thinks that we should use what is on the signs there, just because that is what references the place when you are physically there (and predominantly where we get new data from), but it seems silly to fight it.

Problem is signs may be inconsistent. Around here you’ll see parkway abbreviated as Pkwy or Py, boulevard as Blvd or Bv, and so on.

The Post Office has a standard set of abbreviations for words like street, boulevard etc. Use these, make them the standard and save time and space.

Do all national post offices have standard abbreviations?

As NE2 rightly asks, do all national post offices use a consistent set of abbreviations? No, OSM’s existing policy is a far, far better way of dealing with the issue.