(this is common for file magic numbers). These mixed binary-and-text file are usually regarded as "binary", because an application that can only process text will not know what to do with them.

It is quite common for a text file to use its text to encode data that could be encoded in binary some other way; a text file that does this is still regarded as a text file, and not a binary file, so long as it remains within the previously-stated constraints about what the bits of the file represent.