string of three alphabetic characters.
RFC 1945 HTTP/1.0 May 1996
A construct "#" is defined, similar to "*", for defining lists
of elements. The full form is "#element" indicating at
least and at most elements, each separated by one or
more commas (",") and optional linear whitespace (LWS). This
makes the usual form of lists very easy; a rule such as
"( *LWS element *( *LWS "," *LWS element ))" can be shown as
"1#element". Wherever this construct is used, null elements are
allowed, but do not contribute to the count of elements present.
That is, "(element), , (element)" is permitted, but counts as
only two elements. Therefore, where at least one element is
required, at least one non-null element must be present. Default
values are 0 and infinity so that "#(element)" allows any
number, including zero; "1#element" requires at least one; and
"1#2element" allows one or two.
A semi-colon, set off some distance to the right of rule text,
starts a comment that continues to the end of line. This is a
simple way of including useful notes in parallel with the
The grammar described by this specification is word-based.
Except where noted otherwise, linear whitespace (LWS) can be
included between any two adjacent words (token or
quoted-string), and between adjacent tokens and delimiters
(tspecials), without changing the interpretation of a field. At
least one delimiter (tspecials) must exist between any two
tokens, since they would otherwise be interpreted as a single
token. However, applications should attempt to follow "common
form" when generating HTTP constructs, since there exist some
implementations that fail to accept anything beyond the common
2.2 Basic Rules
The following rules are used throughout this specification to
describe basic parsing constructs. The US-ASCII coded character set
is defined by .
OCTET = <any 8-bit sequence of data>
CHAR = <any US-ASCII character (octets 0 - 127)>
UPALPHA = <any US-ASCII uppercase letter "A".."Z">
LOALPHA = <any US-ASCII lowercase letter "a".."z">
RFC 1945 HTTP/1.0 May 1996
ALPHA = UPALPHA | LOALPHA
DIGIT = <any US-ASCII digit "0".."9">
CTL = <any US-ASCII control character
(octets 0 - 31) and DEL (127)>
CR = <US-ASCII CR, carriage return (13)>
LF = <US-ASCII LF, linefeed (10)>
SP = <US-ASCII SP, space (32)>
HT = <US-ASCII HT, horizontal-tab (9)>
<"> = <US-ASCII double-quote mark (34)>
HTTP/1.0 defines the octet sequence CR LF as the end-of-line marker
for all protocol elements except the Entity-Body (see Appendix B for
tolerant applications). The end-of-line marker within an Entity-Body
is defined by its associated media type, as described in Section 3.6.
CRLF = CR LF
HTTP/1.0 headers may be folded onto multiple lines if each
continuation line begins with a space or horizontal tab. All linear
whitespace, including folding, has the same semantics as SP.
LWS = [CRLF] 1*( SP | HT )
However, folding of header lines is not expected by some
applications, and should not be generated by HTTP/1.0 applications.
The TEXT rule is only used for descriptive field contents and values
that are not intended to be interpreted by the message parser. Words
of *TEXT may contain octets from character sets other than US-ASCII.
TEXT = <any OCTET except CTLs,
but including LWS>
Recipients of header field TEXT containing octets outside the US-