I did some mistakes on my post...

> I tryed to reproduce this in a Delphi application using IBX component. Don't received any deadlock error with read_committed no_wait no_record_version parameters.
> Also, it runs like YOU expected, ignoring uncommitted trans, but reading committed trans, and showing no error in any case.

ops! I must correct that I've tryed with read_committed no_wait record_version and don't *no_record_version* like I've said.
it don't show any error so maybe this a problem with the IBX component... :(
with a no_record_version the application raises a lock conflict.

But I've find that in isql too with record_version it doesn't show any error in my case. only correcting my sqls below so you can try it if you wish.

> But in isql I'm getting the same error here.

...

> set transaction read committed no wait no record version;

sorry, syntax error here, I used the below:
set transaction no wait isolation level read committed no record_version;

> select * from "t";
>
> every thing looks fine.
>
> so let's start second instance:
> isql2:
> CONNECT 'C:\temp\teste.fdb' USER 'SYSDBA' PASSWORD 'masterkey';
> set transaction read committed no wait no record_version;

here too, replace the above line by below:
set transaction no wait isolation level read committed no record_version;

if you the two by
set transaction no wait isolation level read committed record_version;

it should run without errors.

WTH,