One element of an HTTP header value consisting of a name / value pair and a number of optional name / value parameters.

Some HTTP headers (such as the set-cookie header) have values that can be decomposed into multiple elements. Such headers must be in the following form:

header  = [ element ] *( "," [ element ] )
element = name [ "=" [ value ] ] *( ";" [ param ] )
param   = name [ "=" [ value ] ]

name    = token
value   = ( token | quoted-string )

token         = 1*<any char except "=", ",", ";", <"> and
                      white space>
quoted-string = <"> *( text | quoted-char ) <">
text          = any char except <">
quoted-char   = "\" char

Any amount of white space is allowed between any part of the header, element or param and is ignored. A missing value in any element or param will be stored as the empty String; if the "=" is also missing null will be stored instead.