1. A computer program product for protecting data 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: obtaining a virtual address to be translated; obtaining an initial origin address of a translation table of said hierarchy of translation tables, said hierarchy of translation tables comprising a segment table; based on the obtained initial origin, obtaining a segment table entry from said segment table, said segment table entry configured to contain a format control field; in response to an enhanced DAT facility being enabled, determining whether said format control field in said segment table entry is enabled; and in response to said format control field being enabled, performing: obtaining from said translation table entry a segment-frame absolute address of a large block of data in main storage; combining said segment-frame absolute address with a page index portion and a byte index portion of said virtual address to form the translated address of the desired block of data within said large block of data in main storage, said desired block of data consisting of one or more bytes of data; determining whether any DAT protection fields in any translation table entries used in translation of said virtual address are enabled; and in response to all of said DAT protection fields being not enabled, permitting both fetch and store operations to said desired block of data in response to said fetch and store operations being associated with said virtual address.