It makes it difficult in any VCS or diff tool, by default. However they can usually instructed to ignore white-space changes. As an example, in hg I have the f

It makes it difficult in any VCS or diff tool, by default. However they can usually instructed to ignore white-space changes. As an example, in hg I have the following three revisions of a file: abc def ghi abc deg gHi abc d eg gHi Different invocations of hg annotate yield different results, then: > hg blame a.txt 0: abc 2: d eg 2: gHi > hg blame -b a.txt 0: abc 2: d eg 1: gHi > hg blame -w a.txt 0: abc 1: d eg 1: gHi -b ignores changes in the amount of white-space if there was already some (e.g. indenting changes). -w ignores all white-space changes. Generally you can get back to the actual revision where a useful change was made.