General Discussion

Taking very complicated things and making it somewhat easier for people to understand but sometimes that causes certain finer points to get lost.
So the entire system is a lot like other older, large organizations, like a defense contractor, a shipyard, I used to work at, that has a combination of modern computers and Windows and Unix servers managing data in a SAN network and using SQL and Oracle databases. But also running IBM mainframe DB2 and some of the SAN data being manipulated using CA-IDMS, MADAM, and IBM’s VSAM.
Of course the IBM mainframe is using software in COBOL and the CA-IDMS is using the older and likely not used much of anywhere else, CODASYL data model.
Obviously still oversimplifying but I've read 100+ page documents on the IT infrastructure. It's amazing how much about their infrastructure they are willing to share. I've had to look that all up as I'm not a federal employee and have never been one. Fascinating reading though. If you're interested I got give you a link.