Etatmäßige "on the regiment's payroll" ?

[dksck]

In almost all of the explanations of "Etatmäßige" there is a comment about "being on the regiment's payroll," but there is never an explanation of the significance of "being on the regiment's payroll."  Once upon a time, many years ago, I managed to find an explanation, but I've forgotten it!   I seem to recall there were at least a couple of important differences between those on the regiment's payroll and those who were not.  When you got paid?  How often you got paid?  The source of the payment ? Retirement?  Can someone explain to me (again!) the significance of "being on the payroll of a regiment"?  Thank you