The "about:blank" URI [RFC6694], when used as a problem type,

indicates that the problem has no additional semantics beyond that of

the HTTP status code.

When "about:blank" is used, the title SHOULD be the same as the

recommended HTTP status phrase for that code (e.g., "Not Found" for

404, and so on), although it MAY be localized to suit client

preferences (expressed with the Accept-Language request header).

Please note that according to how the "type" member is defined

(Section 3.1), the "about:blank" URI is the default value for that

member. Consequently, any problem details object not carrying an

explicit "type" member implicitly uses this URI.