Okay, I'm going to do my best to remember the details. It had something to do with where the service was performed related to that account...

Code 1 is Early, and Penalized

Code 4 is Dead Person = not your retirement, but paid because of the dead person

Code 7 is Normal, so your retirement and this is what the details referred to, for sourced to MS is nontaxable

Code 2 is Early, but the withdrawal met an exception for the penalty.

This is from MS law:

Amounts received as retirement allowances, pensions, annuities or optional retirement allowances from any Federal, State, and Private retirement system or plan are exempt from State Income Tax.

and then:

Early distributions from retirement plans do not qualify for this exemption. Although these amounts are subject to state income tax, there is no early withdrawal penalty for state purposes.