[root@develop firebird-4.0]# bin/isql tst4
Database: tst4, User: SYSDBA
SQL> CREATE TABLE DEMO (ID INT128);
Statement failed, SQLSTATE = 42000
Dynamic SQL Error
-attempted update during read-only transaction

SQL> show version;
ISQL Version: LI-V4.0.2.2816 Firebird 4.0
Server version:
Firebird/Linux/AMD/Intel/x64 (access method), version "LI-V4.0.2.2816 Firebird 4.0"
on disk structure version 13.0

CREATE DOMAIN T_MOMENT AS 
TIMESTAMP
DEFAULT LOCALTIMESTAMP;
...
CREATE TABLE FSNAPSHOT (
...
    MOMENT T_MOMENT,
...