RFC1866 (November 1995, Hypertext Markup Language - 2.0) is the first HTML-related RFC. Says the W3C, “It set the standard for core HTML features based upon current practice in 1994.” More recent HTML specifications—for HTML 3.2 and 4.0—are not part of the RFC set but can be found on the W3C site (http://www.w3c.org/).
The mechanism described in RFC1867 (November 1995, Form-based File
Upload in HTML) remains one of the primary tools used to enable a
two-way flow of data in web-based systems. RFC1867 also suggests the
idea, later adopted in the HTML standard, that forms can use
ACTION=mailto: to transmit field data by way of