Bingo! I just found http://arstechnica.com/information-technology/2016/05/government-agencies-keep-sacrificing-cash-to-zombie-it-systems-gao-finds/ http://arste

Bingo! I just found http://arstechnica.com/information-technology/2016/05/government-agencies-keep-sacrificing-cash-to-zombie-it-systems-gao-finds/ http://arstechnica.com/information-technology/2016/05/govern... mentioning both Individual Master File and Business Master File written in IBM mainframe assembler 56 years ago. Joy. Although I suspect it's a bit of an exaggeration because it seems the IRS is using System/360 which started 1965 https://books.google.ca/books?id=HwniRloeB6cC&pg=PA2&lpg=PA2&dq=ibm+360+irs+%22master+file%22&source=bl&ots=DNqni9DXg1&sig=ag4xDy_ERLUjJeslLy3sIq5rUks&hl=en&sa=X&ved=0ahUKEwix8Krp_PnMAhUGyWMKHfoGA0sQ6AEIKjAB#v=onepage&q=ibm%20360%20irs%20%22master%20file%22&f=false https://books.google.ca/books?id=HwniRloeB6cC&pg=PA2&lpg=PA2...