Delphi Anti-Corrosion Pollen

I don't know what you mean by "creating an autoinc field in firebird with Zeos". The autinc fields and the whole database structure are usually defined in a SQL script that can be executed by a variety of tools. I used Firebird 2.1 in my recent project (using FibPlus 6.9.9) and wrote some posts about it, maybe the following will help:

Part 1 - Introduction

Part 4 - Autoincrement Fields