At a high level of abstraction, a digital or computer file is a stored segment or block of information that is available to a computer program. Files are so named because they are the counterparts of the paper documents traditionally kept in file folders, usually stored in a file cabinet. Computer operating systems consider files as a sequence of bytes, while application software interprets the binary data as, say, text characters, image pixels, or audio samples.
This term is comparable to the term file as defined in Introduction and Supporting Materials from PREMIS Data Dictionary (p. 7): "A file is a named and ordered sequence of bytes that is known by an operating system. A file can be zero or more bytes and has a file format, access permissions, and file system characteristics such as size and last modification date . . . . Files can be read, written, and copied. Files have names and formats."
Although this high-level meaning is valid for the Federal Agencies Digitization Initiative, our definition also calls attention to the digital file in relationship to the digital package and the digital package part. Take, for example, the case of a digitally reformatted book or 78 rpm phonodisc. The digital package includes all of the files pertaining to the digitized book or phonodisc. Most reformatting programs will create a set of versioned digital files--perhaps an archival master, a production master, and multiple derivative files--for each book page or disc side (digital item parts). Thus page 3 or side B may be represented by three or four files that meet a variety of objectives.