Structure describing the binary contents of a diff.
A binary file / delta is a file (or pair) for which no text diffs
should be generated. A diff can contain delta entries that are
binary, but no diff content will be output for those files. There is
a base heuristic for binary detection and you can further tune the
behavior with git attributes or diff flags and option settings.
Whether there is data in this binary structure or not.
If this is 1, then this was produced and included binary content. If this is 0 then this was generated knowing only that a binary file changed but without providing the data, probably from a patch that said Binary files a/file.txt and b/file.txt differ.