Foreign server version and type

I'm looking at the CREATE SERVER page on the documentation (http://www.postgresql.org/docs/9.1/static/sql-createserver.html) and noticed that there's a server_version parameter which can be provided with the keyword VERSION and server_type specified after TYPE.

However, there's zero information about what these are used for, whether they have any bearing on anything or why you'd want to use them.  Are these parameters used for anything, or are they purely for future functionality?  Whatever the case, could some kind of elaboration be added to justify the existence of these options?  They have been in the docs since the CREATE SERVER syntax was introduced in 8.4.

Thanks
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Thom Brown
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