Details about libpq cross-version compatibility

Hello,

I believe there is some info missing in the page describing libpq programs build:

http://www.postgresql.org/docs/9.2/interactive/libpq-build.html

I am working with PostgreSQL for several years now (since V7), maintaining a set
of "db drivers" for our system, that can be used with the different PostgreSQL
versions.

We need to build our binaries for different versions of PostgreSQL, today it's
from 8.3 to 9.2 ...

What is the compatibility rule regarding this?

Can I compile / link with a PostgreSQL 9.1 environment and deploy on 9.2 ???

Can I compile / link with a PostgreSQL 8.x environment and deploy on 9.x ???

The problem is that we have to ship several versions of the drivers for all
the PostgreSQL versions that are in the support live cycle, today this is
from 8.3 to 9.2 ...

So far, we followed the version policy as described here:

http://www.postgresql.org/support/versioning

I think it's ok to follow this rule, but would feel much better if it was
clearly stated in the "Building libpq Programs" page.

Thanks!
Seb