It is expected that many other subtypes of application will be defined in the future. MIME implementations must generally treat any unrecognized subtypes as being equivalent to application/octet- stream.
The formal grammar for content-type header fields for application data is given by:
application-type := "application" "/" application-subtype
application-subtype := ("octet-stream" *stream-param)
/ "postscript" / extension-token
stream-param := (";" "type" "=" value)
/ (";" "padding" "=" padding)
padding := "0" / "1" / "2" / "3" / "4" / "5" / "6" / "7"