When the APPID in DBQL is recorded as 'Queryman' and when it is recorded as 'SQLA'?
Versions up to and including 12.0 would be recorded as Queryman.
Version 13.0 and later will be recorded as SQLA.
(I'm assuming you are refering to the application name field in the logon source)
I was asking about the APPID column in DBC.DBQLOGTBL but correlating that column with logonsource in DBC.logonoff, it is one and the same thing.