Git interprets a zero byte as an unconditional sign that a file is a binary file [0]. With other “nonprintable” characters (including the high-bit ones) it depe

Git interprets a zero byte as an unconditional sign that a file is a binary file [0]. With other “nonprintable” characters (including the high-bit ones) it depends on their frequency. Other tools look for high bits, or whether it’s valid UTF-8. PDF files usually have a comment with high-bit characters on the second line for similar reasons. These recommended rules cover various common ways to check for text vs. binary, while also aiming to ensure that no genuine text file would ever accidentally match the magic number. The zero-byte recommendation largely achieves the latter (if one ignores double/quad-byte encodings like UTF-16/32). [0] https://github.com/git/git/blob/683c54c999c301c2cd6f715c411407c413b1d84e/convert.c#L98 https://github.com/git/git/blob/683c54c999c301c2cd6f715c4114...