stability of pg library usage

Hi,

we developed some software using the C-library for pg 7.1.3 and distributed it
to users who are using pg 7.2.x. There was a problem when the program tried
to open 'template1' in order to execute a 'CREATE DATABASE'-statement. The
database 'template1' could not be opened. After installing pg 7.3.1 it
worked.

We are wondering what may have changed in the new version, and if there will
be some stability in the future, so that our software may be used with
different pg versions.

Thanks for replies,

Markus