Maximum MIMEType Length when storing type in DB

What are people using as the length of a MIMEType field in their databases? The longest one we've seen so far is 72 bytes:

application/vnd.openxmlformats-officedocument.wordprocessingml.document

but I'm just waiting for a longer one. We're using 250 now, but has anyone seen a longer MIMEType than that?

Edit: From the accepted answer, 127 for type and sub-type each, so that's 254 max, plus the '/' is a limit of 255 for the combined value.

Solution 1:

According to RFC 4288 "Media Type Specifications and Registration Procedures", type (eg. "application") and subtype (eg "vnd...") both can be max 127 characters. You do the math :)

Edit: Meanwhile, that document has been obsoleted by RFC 6838, which does not alter the maximum size but adds a remark:

Also note that while this syntax allows names of up to 127 characters, implementation limits may make such long names problematic. For this reason, <type-name> and <subtype-name> SHOULD be limited to 64 characters.