Z:gnu-www-ja-gpl-faq--2b6274-Complete corresponding source/en

Complete corresponding source means the source that the binaries were made from, but that does not imply your tools must be able to make a binary that is an exact hash of the binary you are distributing. In some cases it could be (nearly) impossible to build a binary from source with an exact hash of the binary being distributed &mdash; consider the following examples: a system might put timestamps in binaries; or the program might have been built against a different (even unreleased) compiler version.