The majority of the columns on the AlarmTransactionLog table are defined as CHAR rather than VARCHAR. Why is this? I ask because I want to convert the columns to VARCHAR to save space.
You can safely change the CHAR to VARCHAR. The NIS Bridge in NAS 3.xx (supporting SQLSERVER, Oracle and MySQL) uses VARCHAR. The table you are refering to, is utilized by the ADO gtw and an early method of storing NAS alarms into e.g. SQL server (or any other database with a supported ADO driver). With NAS 3.xx, you have the option to configure the NIS bridge to do the same type of storage of alarms (open alarms, alarm transactions and notes).
Retrieving data ...