mimetype:file_content

True if File should be served using ContentType: ContentType. It takes the following steps:

Determine the media type using file_mime_type/2, unless already specified using file_content_type/3.
Determine it is a text file using text_mimetype/1
Use the charset from the Prolog flag default_charset

The behavior is controlled by several hooks and a flag.

mime:mime_extension/2 defines the media type
text_mimetype/1 defines the media type is text
mime:charset/3 derives the charset for a file with a given media type, if the media type is text according to text_mimetype/1.
If text_mimetype/1 succeeds and mime:charset/3 fails, the flag default_charset defines the charset unless it is set to -. The flag set by default to UTF-8 if the Prolog flag encoding is set to utf8.