Zero-byte file
Even a file describing an empty word processor document , an image file with zero-by-zero dimensions , or an audio file of length zero seconds usually still contains metadata identifying the file format and describing some basic attributes of the file; it results in the file with some positive size . 
<triplet> image file <subj> file format <obj> subclass of <triplet> audio file <subj> file format <obj> subclass of