以下核心规则包含在RFC RFC347的附录B.1中:ALPHA(字母),CR(回车),CRLF(CR LF),CTL(对照),DIGIT(十进制0-9) ,DQUOTE(双引号),HEXDIG(十六进制0-9 / AF / a-f),HTAB(水平制表符),LF(换行符),OCTET(任何8位数据序列),SP(空格)和VCHAR 任何可见的US-ASCII字符)。
下面的规则定义在RFC7230中:
OWS = <OWS, see [RFC7230], Section 3.2.3>
field-name = <field-name, see [RFC7230], Section 3.2>
quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
token = <token, see [RFC7230], Section 3.2.6>
port = <port, see [RFC7230], Section 2.7>
pseudonym = <pseudonym, see [RFC7230], Section 5.7.1>
uri-host = <uri-host, see [RFC7230], Section 2.7>
下面的规则定义在其他部分:
HTTP-date = <HTTP-date, see [RFC7231], Section 7.1.1.1>