1. A computer program product for translation of a virtual address into a translated address of a desired block in main storage in a computer system of a machine architecture, the computer program product comprising: a storage medium readable by said computer system, said computer readable medium storing instructions for performing: based on an initial origin address of a translation table of a hierarchy of translation tables comprising a segment table, obtaining a segment table entry from said segment table, said segment table entry configured to include a format control field; based on an enhanced Dynamic Address Translation (DAT) facility being enabled, determining whether said format control field consists of an enabled value or a not-enabled value, wherein the enabled value of the format control field indicates the segment table entry is configured to consist of a first set of functional fields, a second set of functional fields and a segment-frame absolute address of a large block of main storage, wherein the not-enabled value of the format control field indicates the segment table entry is formatted to consist of the first set of functional fields and an origin address of a page table; and based on said determining said format control field is enabled, a processor performing: obtaining from said segment table entry, by the processor, said segment-frame absolute address of said large block of main storage; combining, by the processor, said segment-frame absolute address with a page index portion of said virtual address and a byte index portion of said virtual address to form the translated address of the desired block of main storage within said large block of main storage, wherein the formed translated address consists of said segment-frame absolute address, said page index portion of said virtual address, and said byte index portion of said virtual address, wherein said desired block of main storage consists of one or more bytes of data; and accessing said desired block of main storage addressed by said translated virtual address.