[GENERAL] libecpg versions and libecpg_compat

Hi Hackers,
I posted this to the GENERAL list a while back, but got no repies. 
Perhaps someone here can help...

I've been building ECPG (embedded SQL/C) programs on a system with 
Pg version 8.0 installed.  When I tried to run them recently on 
version 8.4 I found that there was a libecpg library 
incompatibility:  v8.0 uses libecpg.so.5, whereas 8.4 uses libecpg.so.6.

Then I noticed libecpg_compat in the lib area.  What is this used 
for?  "compat" suggests compatibility between different versions? 
But Pg 8.0 has libecpg_compat.so.2, whereas Pg 8.4 has 
libecpg_compat.so.3.

Is there some way of building with Pg v8.0 ECPG lib and running on a
system with Pg v8.4 ECPG lib?  or vice versa? and is libecpg_compat
intended for that purpose?

Thanks,
Rob