A brief review for the uninitiated. Two rules:

1. An engine cannot open a database with a different ODS major
version number
2. An engine can open a database with a minor version number <= the
engine's minor version

An ODS major version number change is major intergalactic extinction
event and is extraordinarily rare.

An ODS minor version number change is small potatoes and has very few,
if any ripples.

Change the interpretation of Hdr::pageSize (or whatever it's called in
Firebird) is no problem if the minor version number is bumped. Old
versions of the engine won't touch it with a ten foot (3M) pole, but new
versions with use the actual minor version number of a database to
interpret the field.

Sean's hack is really a hack at all, but a perfectly reasonable
redefinition of a field, one of those things that happens when we live
long enough to get smarter.

--
Jim Starkey
President, NimbusDB, Inc.
978 526-1376