Description of the OBJECT element of the HTML 4.0 draft

This document describes the OBJECT element as defined in the HTML 4.0 draft. Being a working draft, it may change at any time, and such changes may not be reflected in this document. Please do not assume that Web browsers support the features described herein, even if they are announced as having OBJECT support.

Contents

• Preface
• Background: OBJECT as generalization of IMG
• The basic idea of OBJECT (not written yet)
• Specifying the rendering mechanism (not written yet)
• Presentational features (not written yet)
• Image maps and the OBJECT element (not written yet)
• A thematic description of all attributes of OBJECT (being written right now)
• All attributes of OBJECT in alphabetic order (not written yet)

Preface

Thus, this document tries to be descriptive. I have written separate criticism of the HTML 4.0 draft which includes critical remarks on the OBJECT element, too, although it comments that element as one of the most important things in the draft.

The reader is assumed to know the basics of the HTML language, as described in my Getting Started with HTML or some of the other primers on HTML. No specific knowledge about some particular HTML version is required, but for some details which relate to the HTML 4.0 draft as a whole, the reader should consult that draft.

Background: OBJECT as generalization of IMG

Later various optional attributes have been added to the definition of the IMG element. See, for example, a description of the IMG element as defined in HTML 3.2. However, these additions mainly relate to details of the presentation of images, although some additions have been made in order to support image maps.

On the other hand, images are just one form of illustration which people wish to use on Web pages. Animations, videos, and sounds would often be more useful than static images. (It is possible to use a simple IMG element for a graphics file which effectively looks like a short animation, but this feature isn't very powerful.)

The (hyper)link concept and the related A element has always been available in HTML for referring to various illustrations implemented in different media. For example, a hyperlink might provide an easy way to the reader to request (typically with a mouse click) a song to the played or a video shown, provided of course that suitable devices and software are available, installed and enabled. This simple facility should not be underestimated. One might well argue that most advanced illustrations should be implemented that way, allowing each reader to select what he wants to see or hear. However, the HTML 4.0 draft presumes that there are occasions where it makes sense to embed e.g. sounds or animations onto a Web page - or that authors will do that anyway.

In various nonstandard versions of the HTML language, such as the dialects supported by Internet Explorer or Netscape, there are different methods for embedding different media types onto a Web page, such as EMBED or BGSOUND for sounds. Moreover, some of such methods were taken into the HTML 3.2 standard: APPLET element for using Java applets and SCRIPT element for using client-side scripts. Both of these can be used to include animations onto Web pages, for example.

One of the aims of proposing the OBJECT element is to provide a more general facility. A simple IMG element like

<IMG SRC="decor.gif" ALT="">

<OBJECT TYPE="image/gif" DATA="decor.gif"></OBJECT>

A thematic description of all attributes of OBJECT

element-specific attributes

Attributes which relate to the fundamental meaning of the OBJECT element. Some other elements may have attributes with the same names, but their meaning may vary. These attributes can be divided into two subsections:

• attributes related to specifying the object itself
• attributes related to specifying the rendering mechanisms

special attributes

Attributes which relate to some special use of the element or to using it in conjunction with another element in the HTML language. These attributes can be divided into three subsections:

• attributes related to applets
• attributes related to image maps
• attributes related to forms

presentational attributes

Attributes which specify presentation properties such as alignment of dimensions. Deprecated in favor of style sheets.

general attributes

Attributes which can be attached to a wide range of elements in the HTML language, with the same basic meaning in each. These attributes can be divided into two subsections:

• "core attributes" for naming an element instance or attaching a class or a title to it or specifying a style sheet for it
• attributes for natural language support ("internationalization", "i18n")
• attributes for event handling.

• its name
• its basic meaning in a few words
• its set of possible values, either by referring to a term and associated description, or by enumaterating them; in the latter case, the meaning of each value is explained separately; the default value is marked using emphasis
• the meanings of the values if enumerated, or explanations otherwise.

A length specification can be given either as an absolute number of pixels or as a percentage such as "50%". The HTML 4.0 draft says in a comment in the DTD that the length specifications are suggested heights, widths, etc. On the other hand, the longer descriptions of the attributes do not refer to suggesting anything. They even say that the HEIGHT and WIDTH attributes "tell user agents to override the natural image size and scale the image to this width and height".