You can contrast that with full preservation. FCLA says:
Full preservation includes bit-level preservation of the originally submitted files, as well as services intended to ensure that the information content of the files will remain usable into the indefinite future. These services vary according to the file type but may include the creation of normalized forms of the file and/or the reformatting of obsolete formats to reasonably comparable successor formats. It is not guaranteed, however, that normalized or migrated versions of any file will be identical in functionality or in look and feel to the original file. Note also that if a logical object is comprised of individual files in both supported and unsupported formats, there is no guarantee that the logical object will remain usable as intended.The assumption is, of course, that you have defined what file types you want to do full preservation on and why, and that those decisions match your organization's needs.
At any rate, these are both good definitions to keep handy. A Google search doesn't show bit-level preservation to be use widely at the moment, but I'm sure it will be.