what file extensions must be explicitly configured with respect to eol-type in gitattributes?

Hello,

One project we have in house has approximately 160 different file extensions used for the files checked in. In our repository there are files that MUST be CRLF (.bat, .cmd, .vcproj, etc), files that MUST be LF (.xml, .xsl, .sh, etc), and files that MUST be binary. All others are just text and so long as they appear in native form I'd be happy.

It would seem a default rule to handle text files would make sense:

* text=auto

But I have not found material explaining how git identifies binary files, so one concern would be that it could mangle binary file types in some cases.

Do I have to explicitly mention all 160 file types in the gitattributes file?

How does git internally determine whether a file is text vs binary? Does it use the 'file' command in Unix?

And where I am going with this specifically is a question: what rules MUST be specifically stated in gitattributes and what rules are there implicitly?

Thank you,

Bob