Appendix A: Changes

A.1 Changes between 24 April 1998 HTML 4.0 and 24 December 1999 HTML 4.01 versions

This section describes how the 24 December 1999 version of the HTML 4.01 specification differs from the 24 April 1998 version of the HTML 4.0 specification.

A.1.1 Changes to the specification

General changes 

• New style sheets for the document based on W3C technical report styles.
• Added a short table of contents.
• Updated the copyright.
• Fixed document scripts to remove markup causing crashes on some browsers.
• Thanks to Shane McCarron added to the acknowledgments.
• In section 1.4, removed copyright details and refer to W3C site instead.
• References to the document character set are all ISO 10646 (and one time to UNICODE to signal equivalence). References to UNICODE refer only to the bidirectionality algorithm.
• Examples now use dated FPIs.

On SGML and HTML 

• Section 3.2.2: Attribute values may contain colons and underscores as well.

HTML Document Representation 

• The Document Character Set: [ISO10646] now used only for references to the document character set. [UNICODE] is reserved for bidi-related references.

Basic HTML data types 

• Media descriptors: All characters in examples now described using hex notation (and reference to ISO 10646 rather than Unicode).

Global structure of an HTML document 

• 7.2 HTML version information: Add a note about the HTML WG's commitment that
  • Any changes to future HTML 4 DTDs will not invalidate documents that conform to the DTDs of the present specification. The HTML Working Group reserves the right to correct known bugs.
  • Software conforming to the DTDs of the present specification may ignore features of future HTML 4 DTDs that it does not recognize.
• 7.2 HTML version information: Use undated, HTML 4 URIs for system identifiers. These URIs are also used globally in all examples.
• 7.4.4 Meta data: Removed note about ongoing work at W3C on meta data and replaced with a note about RDF.
• 7.4.4.2 Meta data: At the end of the section on HTTP headers, removed the auto-refresh example (since not part of the Recommendation) and added a note to use server-side redirects.

Language information and text direction 

• The dir attribute: Clarification that dir applies to element content, attribute values, and table direction.

Tables 

• 11.2.6 Table Cells: The definitions of rowspan and colspan changed. Now spans are bounded by groups (rowgroups or colgroups).
• 11.3.2 Table Cells: When "char=align" not supported by the user agent, behavior is undefined.

Links 

• 12.2 The A element: The description of the type attribute for the A and (LINK) elements has been modified to emphasize its advisory nature.
• 12.2.3 Anchors with the id attribute: It is legal for "name" and "id" to appear in the same start tag when they are both defined for an element. They must have identical values.
• 12.3.3 Links and search engines: Removed reference to dir attribute in example since it doesn't apply to linked resources (only element content and attribute text values).
• 12.4.1 Resolving relative URIs: Since RFC 2616 does not include a Link header field, the following statement is qualified for earlier versions of HTTP 1.1: "Link elements specified by HTTP headers are handled exactly as LINK elements that appear explicitly in a document."

Objects, Images, and Applets 

• 13.2 The IMG element: Addition of the name attribute for backwards compatibility.
• 13.2 The IMG element: Added a note that user agents must provide different mechanisms for accessing the "longdesc" URI (of IMG) and the "src" URI (of A) when an IMG is part of the content of an A element.
• 13.3 The OBJECT element: Added a note that when the value of "type" for OBJECT and the Content-Type HTTP header differ, the latter takes precedence.
• 13.3 The OBJECT element: Added a statement to use PARAM instead of the "data" and "classid" attributes for OBJECT together.
• 13.4 The APPLET element: Added a note that, for security reasons only subdirectories are searched for the "codebase" attribute of APPLET.
• 13.6.1 Client-side image maps: The definition of the "poly" attribute has been cleared up. There is a note that if not closed by authors, user agents should close the polygon for the "coords" attribute of AREA.
• 13.6.1 Client-side image maps:
  • The content model of the MAP element now allows authors to mix AREA content and block-level content.
  • User agents "should" render block-level content (used to be "may").
  • The MAP element may be used without an image for general purpose navigation tools.
  • User agents must ignore AREA elements when content is mixed (AREA and block level).
  • Authors should specify geometries completely with either AREA elements, or A elements in block content, or both.
• 13.7.2 and 13.7.3 : The vspace and hspace attribute definitions now look like the definitions of other attributes.
• 13.7.2 and 13.7.3 : The type of vspace, hspace, and border attribute values was changed from "length" to "pixels".
• 13.8 Alternate text: The last sentence of section now links to notes for user agent developers for handling empty "alt" attribute text.

Style Sheets in HTML Documents 

• 14.6 Linking to style sheets with HTTP headers: Since RFC 2616 does not include a Link header field, the entire section is qualified to pertain only to earlier versions of HTTP 1.1.

Frames 

• 16.4.1 NOFRAMES: Added text to the NOFRAMES description about rendering when (1) frames turned off (2) frames not supported.
• 16.4.1 NOFRAMES: Added text about which DTDs may have NOFRAMES (frames, transitional).

Forms 

• 17.2.1 Control types: In the description of radio buttons, when no radio button is initially selected, user agent behavior for selecting one is undefined. This differs from RFC 1866.
• 17.3 The FORM element: Addition of the name attribute for backwards compatibility.
• 17.3 The FORM element: Removed the reference to the "mailto" URI in the "action" attribute definition.
• 17.3 The FORM element: Removed "mailto" example near end of section since behavior not defined in this spec.
• 17.3 The FORM element: The accept attribute is added to the DTD fragment. Also, the description of the accept-charset attribute is amended.
• 17.4 The INPUT element: Added missing "ismap" for the INPUT element. Also, in definition of value., add "checkbox" to values of type that require a value.
• 17.6.1: When no option is preselected, user agent behavior is undefined. Authors should supply and explicit none option to cover this case. This behavior differs from RFC 1866.

SGML Declaration 

• SGML Declaration of HTML 4: Removed text about up-to-date references to ISO 10646. Replaced with: "Revisions of the HTML 4 specification may update the reference to ISO 10646 to include additional changes."

Strict DTD 

• vspace/hspace/border attributes for IMG, OBJECT, APPLET in pixels.
• Changed content model of MAP to ((%block;) | AREA)+
• Added "ismap" attribute to INPUT
• The accept attribute is added to the DTD fragment for the FORM element.
• The axis attribute comment has been changed to refer to a comma-separated list.
• The archive attribute for the OBJECT element takes a value of type CDATA instead of type %URI since the value is a space-separated list of URIs.

Notes 

• Notes Updated notes on accessibility to point to Web Content Accessibility Guidelines.

References 

• Updated links to RFCs to use http://www.ietf.org/rfc
• Put links in titles.
• Added revised date of 27 Aug 1998 for [DATETIME]
• Added revised date of 11 Jan 1999 for [CSS1].
• Publication date of [CSS2] fixed.
• [UNICODE] has been updated to version 3.0
• [ISO10646] has been updated to allow for new character assignments. Note that amendment five is specifically taken into account.
• [RFC1766] expected to be updated.
• [RFC2279] obsoletes [RFC2044].
• [RFC2616] obsoletes [RFC2068].
• [RFC2388] added in addition to [RFC1867].
• [LEXHTML] address updated, date added.
• [DCORE] address updated.
• Updated [WEBSGML]
• [HTML3STYLE] address updated.
• Added [RDF10] (replaced old RDF)
• Changed [WAIGUIDE] -> [WAI]
• Added informative references [WCGL], [UAGL], and [ATGL]
• Updated URI reference to [URI] (RFC 2396).

A.1.2 Errors that were corrected

Section 13.6.1

Image map examples using "poly" have been fixed to form a closed polygon. Also, the last pair of coordinates is the same as the first to close the polygon.

Section 14.4.1

In the final example, the STYLE element is missing the attribute assignment "media=screen, print".

Section 15.2.1

In the example with "mypar", the CSS rule should read

  P#mypar {font-style: italic; color: blue}

In CSS, "#" refers to an ID name while the "." refers to a class name. This example is dealing with the "id" attribute.

Section 16.2.2

Values for marginwidth and marginheight must be 0 pixels or more, not 1 pixel or more.

Section 16.2.2

The FRAME element does not take the target attribute.

Section 16.5

The IFRAME element does not take the target attribute.

Section 17.2.1

In the description of "checkboxes", change "selected" to "checked" in "when the control element's selected attribute is set."

Section 17.6.1

In the "Attributes defined elsewhere" section for the OPTGROUP element, the attributes onfocus, onblur, and onchange should not be there.