content_length

Converted into an integer

status

Converted into an integer

cookie

Converted into a list with Name=Value by cookies//1.

set_cookie

Converted into a term set_cookie(Name, Value, Options). Options is a list consisting of Name=Value or a single atom (e.g., secure)

host

Converted to HostName:Port if applicable.

range

Converted into bytes(From, To), where From is an integer and To is either an integer or the atom end.

accept

Parsed to a list of media descriptions. Each media is a term media(Type, TypeParams, Quality, AcceptExts). The list is sorted according to preference.

content_disposition

Parsed into disposition(Name, Attributes), where Attributes is a list of Name=Value pairs.

content_type

Parsed into media(Type/SubType, Attributes), where Attributes is a list of Name=Value pairs.

expires

Parsed into a time stamp using http_timestamp/2.

As some fields are already parsed in the Request, this predicate is a no-op when called on an already parsed field.