Appendix A:
The differences between HTML 3.2 and HTML 4.0

A.1 Differences in cell

A.1.1 New items

In HTML 4.0 the following new elements are introduced: the ABBR , ACRONYM , of BDO , to BUTTON , the COLGROUP , the DEL , the FIELDSET , the FRAME , a FRAMESET , the IFRAME , the INS , the LABEL , LEGEND , the NOFRAMES , a NOSCRIPT , the OBJECT , the OPTGROUP , the PARAM , the SPAN , TBODY , TFOOT, , THEAD and the Q .

A.1.2 Undesirable elements

The following elements are undesirable : the APPLET , BASEFONT , CENTER's , the DIR , the FONT , ISINDEX , the MENU , the S , STRIKE and the U .

A.1.3 Obsolete elements

The following elements are obsolete: LISTING, PLAINTEXT, and XMP. Instead, authors should use the element of the PRE .

A.2 Differences in attributes

• Almost all attributes that specify presentation of a document HTML (colors, alignment, fonts, graphics, etc.) are undesirable , it is recommended to replace isoplzovat stylesheet. In the list of attributes in the appendix indicates which attributes are undesirable .
• The attributes id and class allow authors to assign the elements of information about the name and class for the stylesheet, anchors, scripts, ads facilities, common document processing, etc.

A.3 differences in accessibility

In HTML 4.0 has many changes regarding the availability , including:

• Attribute title can now be installed for almost every element.
• Authors may We point out long descriptions of tables, images and frames (see. The longdesc attribute).

A.4 Differences in meta

Now, authors can define profiles with descriptions of the metadata elements defined in the META or the LINK .

A.5 Differences in the text

• New internationalization allow authors to specify text direction and language.
• Elements of INS and DEL allow to mark the changes in the documents.
• Elements ABBR and ACRONYM let you mark up documents abbreviations and acronyms.

A.6 Differences in links

• Attribute id allows you to make any element the destination anchor links.

A.7 Differences in the tables

HTML 4.0 table model derived from the work on HTML + and nachlanogo draft HTML3.0 . Past at the request of the information provider model is extended as follows:

• Authors may specify tables that are displayed sequentially as data is received by the user agent.
• Authors may specify tables that are more accessible to non-visual polzvoatelyam agents.
• Authors may specify tables with fixed headers and footnotes. User agents may use this benefit when scrolling large tables or in the presentation on paged media.

HTML 4.0 table model also provides an optional default settings depending on the column for alignment, greater flexibility in defining boundaries and frame tables and the ability to align on certain characters. However, it is expected that a task of presentation tables in the near future will assume stylesheet .

In addition, the main objective was to ensure compatibility with the widely used by Netscape implementation of tables. Another objective was to simplify importing tables conforming to the SGML CALS model. In the latest draft of the attribute align is compatible with the latest versions of most browsers populyarnyz. Made some clarifications in the role attribute dir and recommended behavior when used mixed absolute and relative column widths.

A new element, the COLGROUP , allows you to group sets of columns with different width and alignment properties specified by one or more elements of the COL . Compared to previous drafts, the semantics element explained the COLGROUP , and rules = "basic" replaced by rules = "groups".

Attribute style is used as a means of extending the properties associated with groups of cells. For example, the line style: dotted, double, thin / thick etc .; color / shading for internal content; a field of cells, and font information. This is the topic of specification on style sheets.

Attributes frame and rules modified to avoid SGML name clashes with each other and to avoid clashes with attributes align and valign . The motive for these changes as was the desire to avoid future problems if this specification is extended to allow the attributes frame and rules in other table cells.

A.8 for images, objects, and image maps

• Element OBJECT used for general switching facilities.
• Elements IFRAME and OBJECT allow authors to create embedded documents.
• Atirbut alt required elements IMG and the AREA .
• A mechanism for creating image maps now allows authors to create more accessible image maps. The content model element MAP for that reason changed.

A.9 Differences in forms

This specification introduces several new attributes and elements related to formm:

• Attribute accesskey allows authors to specify direct keyboard access to form controls.
• Attribute disabled allows authors to turn off the form controls.
• Attribute readonly allows authors zvpretit change form control.
• Element LABEL connects the label with a specific form control.
• Element FIELDSET groups related fields together and, together with the element LEGEND , it can be used to assign a name to the group. Both of these new elements allow better performance and interactivity. Speech-based browsers can better describe the form and graphic browsers can make a valid mark.
• A new set of attributes with scripts allows providers to verify user input.
• Elements BUTTON and the INPUT , whose attribute type set to "button", can be used together with a href = "../ interact / scripts.shtml" > scripts to create a variety of shapes.
• Element OPTGROUP allows authors to group menu items in an element of the SELECT , which is particularly important for form accessibility.
• additional changes in the field of internationalization .

A.10 Differences in style sheets

HTML 4.0 supports a larger set of media descriptors so that authors can write the style sheet, depending on the device.

A.11 Differences in frames

HTML 4.0 supports documents with frames and iframes.

A.12 Differences in scripts

Many elements now have the attributes for the event , which can be combined with scripts; when the event runs a script (for example, when a document is loaded, when the mouse is clicked, etc.).

A.13 Differences in Internationalization

In HTML 4.0 combined recommendations [RFC2070] for the internationalization of HTML.

However, this specification and [RFC2070] differ as follows:

• Attribute accept-charset is now determined for the element the FORM , and not for TEXTAREA and the INPUT .
• The HTML 4.0 specification makes additional clarifications with respect to the bidirectional algorithm .
• Using the element of CDATA to define the elements of SCRIPT and STYLE does not preserve the ability to transcode documents to, as described in section 2.1 [RFC2070] .