1. A computer program product for emulation, by a native computer system of a native machine architecture, of a translation of a virtual address into a translated address of a desired block of main storage of another computer system of another machine architecture, the computer program product comprising: a non-transitory computer readable storage medium readable by said native computer system, said computer readable storage medium storing instructions for performing a method comprising: based on receiving, by the native computer system, a virtual address of the other machine architecture, executing, by the native computer system, program code to perform a method comprising: performing an address translation of a virtual address to obtain an address of a desired block of main storage, wherein the address translation is based on a translation table entry of a translation table, wherein the desired block of main storage has an associated change (C) field for indicating whether said block of main storage has been modified, the C field having a C value; and based on the obtained address, initiating, by the native computer system, a store operation to said desired block of main storage, the store operation (i) causing au associated C field to have a first C value, indicating that the block of main storage has been modified, based on a change override (CO) field of the translation table entry having a first CO value and (ii) not changing the C value of the associated C field based on the CO field of the translation table entry having a second CO value.