HTML+ Document Format Dave Raggett Internet Draft Hewlett Packard 28th October 1993 HTML+ (Hypertext markup format) Status of this memo This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months. Internet-Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet-Drafts as reference material or to cite them other than as a "working draft" or "work in progress". To learn the current status of any Internet-Draft, please check the 1id-abstracts.txt listing contained in the Internet-Drafts Shadow directories on ds.internic.txt, nic.nordu.net, ftp.nisc.sri.com or munnari.oz.au. Distribution of this document is unlimited. Please mail comments to the author at dsr@hplb.hpl.hp.com or to the discussion list: www-talk@nxoc01.cern.ch This draft is valid until May 1st, 1994. It is available in the file draft-raggett-www-html-00.ps and draft-raggett-www-html-00.txt in the internet-drafts directories on the hosts mentioned above. Readers are recommended to try and obtain the Postscript version, which contains figures and formattting examples which are missing from the plain text version. Abstract This draft presents a proposal for a light weight delivery format for browsing and querying information in a web of globally distributed hypertext, accessible over the Internet. HTML+ embodies a pageless model making it suitable for efficient rendering on a wide range of display types, for example, VT100 terminals, X11 Workstations, Windows 3.x and the Macintosh. HTML+ is based upon SGML, and represents document elements at a logical level, e.g. headers, paragraphs, lists, tables, and figures. Authors can choose to create HTML+ documents directly, or to use filters to convert from other formats such as LaTeX, Framemaker, and Word for Windows. HTML+ has grown out of several years experience with the HTML document format in the World Wide Web community. Browser writers are experimenting with extensions to HTML and it is now appropriate to draw these ideas together into a revised document format.. The new format is designed to allow a gradual roll over from HTML, adding features like Internet Draft 1 November 1993 HTML+ Document Format Raggett tables, captioned figures and fill-out forms for querying remote databases or mailing questionnaires. Large documents can be split into a number of smaller nodes for reduced latency, with explicit or implicit navigation links. This draft also includes a proposal to add direct support for mathematical formulae. Authors can include limited presentation hints, and further control may eventually be possible via associated style sheets. Table of Contents HTML+ Discussion Document 4 Introduction 4 Positioning of HTML+ 4 HTML+ and HTML 5 HTML+ and SGML 5 An Overview of HTML+ 6 Document Structure 6 Large Documents 7 Headers 7 Paragraphs and

8 Normal Text 9 Character Sets and Entity Definitions 10 Hypertext Links 11 Character Emphasis 13 Presentation Only Tags 13 Generic Emphasis 13 Logical Emphasis 14 Extending the Set of Logical Roles 15 Annotations 15 Images 15 Change Bars and Document Amendments 17 Conditional Text 18 Explicit Line Breaks 18 Different Paragraph Styles 19 Longer Quotations 19 Abstracts 19 Bylines 19 Notes and admonishments 20 Lists 20 Ordered Lists 21 Bulleted Lists 21 Plain Lists 22 Definition Lists 23 Figures 24 Internet Draft 2 November 1993 HTML+ Document Format Raggett Active Areas 25 Placing Hypertext Buttons on Images 25 Possible extensions 26 Tables 26 Implementation Issues for Tables 28 Fill-out Forms and Input fields 28 Sending form data to an HTTP server 33 Sending a form via Electronic Mail 34 Literal and Preformatted Text 34 Mathematical Equations 36 Indexing 39 Document declarations 40 HTMLPLUS 40 The HEAD and BODY elements 40 TITLE 40 ISINDEX 40 NEXTID 41 BASE 41 LINK 41 Dealing with Large Documents 43 Acknowledgements 45 References 45 Appendix I - The HTML+ DTD 46 Appendix II - Character Entity Names 57 Appendix III - Code for Polygon testing 58 Appendix IV - Sorted list of tags and attributes 60 Internet Draft 3 November 1993 HTML+ Document Format Raggett HTML+ (Hypertext markup format) 1 HTML+ Discussion Document Following the WWW workshop in July 1993 and subsequent discussions on www-talk, it seems an opportune moment to try and reach a consensus before writing a more formal draft as an informational RFC. 1.1 Introduction The World Wide Web is a wide-area client-server architecture for retrieving hypermedia documents over the Internet. It also supports a means of searching remote information sources, for example bibliographies, phone directories and instruction manuals. There are three main ingredients: naming schemes for retrievable objects, protocols and interchange formats. o Universal naming scheme for documents. The Universal Resource Location (URL) syntax specifies documents in terms of the protocol to be used to retrieve them, their Internet Host and path name. A format for location independent lifetime identifiers is currently being defined by a working group of the IETF. A network protocol will allow Universal Resource Numbers (URNs) to be resolved to the URL for the nearest available copy. A URN may specify a number of variants of a document, but the URL will always specify a single copy. o Use of de facto protocols for retrieving documents over the Internet including FTP, NNTP, WAIS, Gopher and HTTP. The latter being designed specifically for the World Wide Web, and uses the MIME message format for document exchange. o A document format supporting hypertext links based on URLs and URNs which can be rendered on a wide variety of display types. HTML+ is intended in this role as a successor to the existing HTML format. HTML+ documents offer a means for providing hypertext links to a variety of media including images, sound sequences, MPEG movies, Postscript files and other formats. These links allow a global web of information sources to be established as new servers and document names are announced. Registers of information sources can also be made available via the web, using its ability to let users search for information via keywords. It is hoped that HTML+ will be useful for information exchange via email and network news as well as HTTP. 1.2 Positioning of HTML+ HTML+ is designed for use in the World Wide Web as a non-proprietary delivery format for wide-area hypertext. It embodies a pageless model making it suitable for efficient rendering on a wide range of display Internet Draft 4 November 1993 HTML+ Document Format Raggett types including VT100 terminals, X11, Windows 3.1 and the Macin- tosh. HTML+ is based upon SGML and represents document elements at a logical level. Authors may choose to create HTML+ documents directly or to use filters to convert from other formats such as LaTeX, Framemaker, and Word for Windows. 1.3 HTML+ and HTML HTML+ is a superset of HTML and designed to allow a gradual roll over from the earlier format, with features like tables, captioned figures and fill-out forms for querying remote data- bases or mailing questionnaires. Large documents can be split into a number of smaller nodes for reduced latency, with explicit or implicit navigation links. This draft also includes a proposal to add support for mathematical formulae. Authors can include limited presentation hints, and further control may eventually be possible via associated style sheets. 1.4 HTML+ and SGML HTML+ is based on the Standard Generalized Markup Language which is an international standard for document markup that is becoming increasingly important. The term markup derives from the way proof-readers have traditionally pencilled in marks that indicate how a document is to be revised. SGML grew out of a decade of work addressing the need for capturing the logical elements of documents as opposed to the processing functions to be performed on those elements. SGML is essentially an extensible document description language, based on a notation for embedding tags into the body of a document' s text. It is defined by the international standard ISO 8879. The markup structure permitted for each class of documents is defined by an SGML Document Type Definition, usually abbreviated to DTD. A lot of work is underway to produce DTDs for a range of purposes. These include ISO 12083 for books and ISO 10744 which defines the HyTime architectural forms for hypermedia/time- based documents. The Text Encoding Initiative (TEI) is an international research project for SGML-based document exchange in the humanities. Publishers are cooperating to produce common DTDs for computer manuals, e.g. the DocBook DTD. The CALS programme of the US Department of Defence defines SGML DTDs for documentation for defence procurement contracts. So what sets HTML+ apart from these efforts? It is impractical to design a DTD to meet the needs of all possible users. Instead, the markup has to be tailored to the needs of a specific community. HTML+ is aimed at fulfilling the dream of a web of information freely accessible over the Internet with links between documents spanning continents. The need to support a very wide range of display types and to keep browser software as simple as possible limits the complexity that can be handled. Similarly the disparate needs of authors has led Internet Draft 5 November 1993 HTML+ Document Format Raggett to the inclu- sion of limited rendering hints. The features supported arise from several years experience with the World Web and the existing HTML format. 2 An Overview of HTML+ HTML+ documents consists of headers, paragraphs, lists, tables and figures. A simple example of an HTML+ document is: A simple HTML+ Document

This is a level one header

This is some normal text which will wrap at the window margin. You can emphasise parts of the text if you wish.

This is a new paragraph. Note that unlike title and header tags the matching end tag is not needed. The text of the document includes tags which are enclosed in . Many tags require matching end tags for which the tag name is preceded by the "/" character. The tags are used to markup the document's logical elements, for example the title, headers and paragraphs. Tags may also be accompanied by attributes, e.g. the id attribute in the header tag which can be used to name destinations for hypertext links. Unlike most document formats, HTML+ leaves out the processing instructions that determine the precise appearance, for instance the font names and point size, the margins, tab settings and how much white space to leave before and after different elements. The rendering software makes these choices for itself (perhaps guided by user preferences). This ensures that browsers can avoid problems with different page sizes or missing fonts. Logical markup also preserves essential distinctions that are often lost by lower level procedural formats, making it easier to carry out operations like indexing and conversion into other document formats. Note that the tag and attribute names are case insensitive. HTML+ parsers are expected to ignore unrecognised tags and attributes, and to process their contents as if the start/end tags weren't present. SGML minimisation is not supported - this avoids any possibility of confusion with unrecognised tags. 2.1 Document Structure An HTML+ document consists of some optional declarations followed by one or more elements from the following: o Headers Internet Draft 6 November 1993 HTML+ Document Format Raggett o Paragraphs o Lists o Figures o Tables o Forms o Literal or Preformatted text o Mathematical formulae 2.2 Large Documents Keeping a large document such as a book in one node will increase the time it takes to retrieve the node over the network. It is generally better to split large documents into a number of smaller nodes. Many documents are written with the expectation that the reader will start at the beginning and read through until the end. If the document is split into a number of nodes, the intended sequence is known as a path. HTML+ provides a means for authors to specify such paths either explicitly via declarations at the beginning of the node or implicitly according to the context in which a given node is reached. Another possibility is for servers to send such information independently, e.g. as MIME message headers. You can provide navigation links for readers which appear as buttons on a toolbar or as entries in a navigation menu. For works using a lot of technical terms or perhaps in an unfamiliar language, you can provide glossaries offering further explanation. Readers can invoke this by double clicking on words, or by drag selection and clicking the Glossary menu item. You can also provide a search field that is always present (and can't be scrolled away), in which readers can enter one or more keywords to search an index. These facilities can be specified explicitly using the LINK element. Implicit links allow you to define the table of contents (toc) as an HTML+ document without needing to place links to the toc in every subdocument. The link back to the toc is implied when you follow hypertext link from the toc to its subdocuments. 3 Headers The tags H1, H2, ... H6 are used to represent headers. H1 is the most significant and rendered in a large font (preferably centered). H2 to H6 are progressively less significant and usually rendered flush left in smaller fonts. A common convention is to begin the body of a document with an H1 header, e.g.

Introduction to HTML+

Internet Draft 7 November 1993 HTML+ Document Format Raggett Header names should be appropriate to the following section of the document, while the title should cover the document as a whole. There are no restrictions on the sequence of headers, e.g. you could use a level three header following a level one header.Header and section elements can take an identifier, unique to the current document, for use as named destinations of hypertext links. This is specified with the ID attribute, e.g.

Introduction to HTML+

This allows authors to create hypertext links to particular sections of documents. It is a good idea to use something obvious when creating an identifier, to help jog your memory at a later date. WYSIWYG editors should automatically generate identifiers. In this case, they should provide a point and click mechanism for defining links so that authors don't need to deal explicitly with identifier names. Automatic generation of IDs for headers, paragraphs and other major elements is important as it makes it easier for other people to create links to your document, by ensuring that there are plenty of ID attributes present as potential destinations. Should we support headers for which the level is implicitly defined by nestable section elements? We could also support autonumbering of headers. Unfortunately, on further investigation these ideas proved trickier than thought at first, and so have been dropped from this draft. 4 Paragraphs and

Normal text is automatically wrapped by the browser at the current window margin and adapts to changes in window size. The text is generally shown in a proportional font:

The P element acts as container for the text between the start tag <P> and end tag </P>. You don't need to give the end tag as it is implied by the context, e.g. the following <P> tag.

If you wish, you may think of the <P> tag as a paragraph separator. This works since HTML+ formally doesn't require you to wrap text up as paragraphs. This would be rendered as: The P element acts as a container for the text between the start tag

and the end tag

. You don't need to give the end tag as it is implied by the context, e.g. the following

tag. If you wish, you may think of the

tag as a paragraph separator. This works since HTML+ formally doesn't require you to wrap text up as paragraphs. Internet Draft 8 November 1993 HTML+ Document Format Raggett The following samples of HTML+ all produce exactly the same results when displayed:

Different ways of using the P element

The first piece of text

The second piece

Different ways of using the P element

The first piece of text

The second piece

Different ways of using the P element

The first piece of text

The second piece They all produce: Different ways of using the P element The first piece of text The second piece In some situations you will want to preserve the original line breaks and spacing, for this you should use the LIT or PRE elements, these are described in a later section. You can force line breaks in normal paragraph text with the
element, but the browser may wrap lines arbitrarily at window margins prior to reaching the
element. The ALIGN attribute can be used to center a paragraph, e.g.

. Other possibilities are ALIGN=left (the default), ALIGN=right, ALIGN=justify and ALIGN=indent. This attribute is a hint and may be ignored by some browsers. Note that when using explicit line breaks (see section 5.12) you may wish to switch off word wrap with WRAP=OFF. Browsers, when parsing paragraphs, can choose to simply treat the

tag as denoting a paragraph break. If the paragraph style includes a blank line between paragraphs, then additional care is needed after headers and other major elements to avoid inserting an unwanted blank line, e.g. when a

tag directly follows a header. This ability to perceive

as a paragraph break provides for continuity with HTML, and allows authors to graduate to treating it as a container in their own time. 5 Normal Text Paragraphs can include the following: o Character entity names for unusual characters such as o which are included using SGML entity definitions: &name; as in "the dream of óengus" which is displayed as: "the dream of oengus". The full list of standard entity names recognised Internet Draft 9 November 1993 HTML+ Document Format Raggett by most browsers is given in Appendix II o Character emphasis using logical and presentational markup. The set of logical character emphasis can be extended, and HTML+ provides the means for browsers to deter- mine how to render such extensions o Simple footnotes or margin notes, which can be rendered as pop-up overlays o Images which act as single characters and which can be vertically aligned relative to the text line in which they are embedded o Hypertext Links based on the URL or URN notations o Markup signifying the start and end of change bars. You can also mark text as being removed or added, as is common in legal documents o Conditional text which appears only on-line or only when printed o Input fields when the paragraph is part of a form o Explicit line breaks 5.1 Character Sets and Entity Definitions By default, HTML+ documents are made up of 8-bit characters from the ISO 8859 Latin-1 character set. The network protocol used to retrieve documents may translate the character set into a locally acceptable form, e.g. EBCDIC. The HTTP protocol uses the MIME standard (RFC 1341) to specify the document type and character set. ISO SGML entity definitions are used to include characters which are missing from the character set or which would otherwise be confused with markup elements, e.g: & ampersand & < less than sign < > greater than sign > " the double quote sign " Appendix II lists a broad range of characters and symbols, relating their ISO names to the corresponding character codes in common character sets. They allow authors to include accented characters in 7-bit ASCII documents. Some other useful entity definitions are: – en dash (half the width of an em unit) — em dash (equal to width of an "m" character)   en space   em space Internet Draft 10 November 1993 HTML+ Document Format Raggett   non breaking space ­ soft hyphen (normally invisible) © copyright sign ™ trade mark sign ® registered sign There are a large number of entities defined by the ISO, covering most languages and symbols for publishing and mathematics. Requiring all browsers to support these would be impractical, e.g. how should a dumb terminal show such symbols. In some cases there will be accepted ways of mapping them to normal characters, e.g. as ae and e as e. Perhaps the safest recommendation is that where authors need to use a specialised character or symbol, they should use ISO entity names rather than inventing their own. Browsers should leave unrecognised entity names untranslated. In some cases it is useful to specify the language used in a given element, with the LANG attribute. The ISO defines abbreviations for most languages, e.g. FR for french as in: Je m'aveugle.. This attribute permits language dependent layout and hyphenation decisions, e.g. Hebrew uses right to left word order. To allow SGML parsers to recognise entity names, authors should declare them before use, for example: %ISOcyr1; This introduces ISOcyr1 as a local name for the ISO public identifier for the cyrillic alphabet and then includes the associated set of entity definitions as part of the current document. This declaration is unnecessary for entities defined within the HTML+ DTD. 5.2 Hypertext Links HTML+ allows authors to embed hypertext links into the document text. In a browser this might look to the reader like: Links are defined with the A tag[1]. HTML+ supports a number of different link types[2]. Clicking on a link will normally cause the browser to retrieve the linked document and display it in place of the current one. This example is represented by the following piece of HTML+ Links are defined with the A tag. HTML+ supports a number of different link types. The first link is to an anchor named "z1" in the current document (using an ID attribute on some element). The second is to a file named "links.html" in the same directory as the current document. The link Internet Draft 11 November 1993 HTML+ Document Format Raggett caption is the text between the start and end tags. The HREF attribute defines the link destination using the URL or URN notations. This may be abbreviated in certain circumstances using relative URLs. The link should be rendered in a clearly distinguishable way, e.g. as a raised button, or with underlined text in a particular color or emphasis. For displays without pointing devices, it is suggested that the link is indicated with a reference number in square brackets after the caption, which the reader enters to follow the link. Note that it is illegal for anchors to include headers, paragraphs, lists etc. The anchor text is restricted to normal text with emphasis and inline images. The A element has several optional attributes: ID This can be used to define a unique identifier for the text contained by the A element. Another document can then make a reference to this by putting the identifier after the URL for this document, separated by a hash sign. The ID attribute replaces the NAME attribute in HTML. HREF This specifies a URL or URN of a linked document which will be retrieved when the user clicks on the anchor's label. HREF=#id can be used for links to other parts of the same document. REL The relationship the linked document has to this one. REL=Subdocument is used to break long documents into smaller ones. This importance of this particular attribute value is explained in section 14. REV The reverse relationship type, and the inverse of REL. EFFECT This determines how the browser displays the linked document when following the link. EFFECT=Replace causes the browser to replace the current document with the linked one; EFFECT=NEW results in the linked document being shown in a new window (if practical); and EFFECT=OVERLAY causes the linked document to be shown in a pop-up window, as used by the Microsoft Windows Help system. PRINT This attribute makes it easy for users to print off the current document and relevant parts. PRINT=REFERENCE (the default) treats the link as a reference, i.e. the URL is given as a footnote; PRINT=FOOTNOTE prints the linked document as a footnote; PRINT=SIDEBAR prints the linked document as a sidebar; and PRINT=SECTION prints the linked document as a follow on section. Use PRINT=SILENT when you don't want the link referenced or printed out. TITLE Defines the title to use when the linked document is otherwise untitled. Internet Draft 12 November 1993 HTML+ Document Format Raggett TYPE The MIME content type of the linked document - for use in providing presentation cues only, as it could easily become out of date. SIZE The size in bytes for the linked document. This should only be used as a guide to progress in retrieving documents, as it is likely to get out of step with changes to the target document. METHODS This is a comma separated list of HTTP methods supported by the linked object. The browser might choose a different way of rendering the link for say searchable objects. SHAPE This is used to define shaped buttons on top of images or figures, and is explained later on. You can also use the LINK element at the start of the document to define document-wide relationships with other documents, e.g. a link to a table of contents. This is described later on. 5.3 Character Emphasis There has been considerable discussion on how to represent character emphasis. The previous draft of HTML+ used a single element to handle all forms with a role attribute for the logical role, and other attributes for providing hints as to how to render the emphasis. This mechanism was seen as being overloaded and prompted the use of separate elements in the current draft. 5.4 Presentation Only Tags In many cases it is convenient to indicate directly how the text is to be rendered, e.g. as italic, bold, underline or strike-through: italic text italic text bold text bold text underlined text underlined text strike through strike through superscript superscript subscript subscript fixed pitch fixed pitch (TT for Teletype) These tags may be nested to combine effects, e.g. bold-italic-fixed-pitch text, and should be considered as hints rather than as binding obligations on the browser, e.g. Some bold italic fixed pitch text. which is rendered as: Some bold italic fixed pitch text. 5.5 Generic Emphasis Internet Draft 13 November 1993 HTML+ Document Format Raggett These are some tags for indicating a level of emphasis without committing oneself to how they should be rendered: normal emphasis typically italic strong emphasis typically bold 5.6 Logical Emphasis These tags indicate the role of the marked text, e.g. bibliographic references. By using a stand- ard way of marking up text, it becomes possible to automatically index such references. There are a potentially huge number of different distinctions that could be made, and the set given below is intentionally minimalistic. Discussion is welcomed on just which elements should be included in HTML+ given its intended role as a delivery format for hypertext documents: q a short quotation which can be included inline, e.g. to be or not to be, that is the question use and in place of double quote marks. cite citation, e.g. Festinger, L.(1957), A Theory of Cognitive Dissonance, Stanford. person proper names, e.g. Albert Einstein acronym acronyms e.g NATO abbrev abbreviations, e.g. v. aux cmd command name, e.g. chmod in Unix arg command argument, e.g. -s kbd something the use would have to type var named place holder, e.g. filename dfn defining instance of a term code code example - usually shown in a fixed pitch font samp sequence of literal characters usually in a variable pitch font All these tags require a matching closing tag like the other emphasis elements, e.g. cmp [-l] [-s] file1 file2 Internet Draft 14 November 1993 HTML+ Document Format Raggett 5.7 Extending the Set of Logical Roles When translating from other SGML-based formats, documents may include non-standard ele- ments e.g. PROPNAME for proper names. HTML+ browsers will normally ignore such markup and process their contents as if these tags weren't present. The RENDER element can be used to tell the browser how to render such tags, e.g. The STYLE attribute is a comma separated list of presentation tag names, i.e. one or more names from the list: I, B, U, S, SUP, SUB, TT. Include P in the list of styles if the element needs a paragraph break. Keeping non-standard markup in HTML+ documents may be useful for indexing purposes. Note that the RENDER element isn't meant to apply retrospectively. 5.8 Annotations Authors can include annotations which act to draw the readers attention or which provide some additional comment on the main text of the paragraph. There are two types: footnote for additional information on some point margin attention getter for this paragraph When printed out, these annotations appear as footnotes or margin notes as their name implies, e.g. This is an example of a footnote . For on-line use, browsers may show the annotation by a hypertext button, e.g. a superscripted dingbat symbol or icon, which when clicked reveals the annotation in a pop-up window. Footnotes and margins can contain text with emphasis and images, but not other markup such as paragraphs, lists or tables. The PANEL element in the previous draft has been dropped. You can however, indicate that a hypertext link should be rendered as a sidebar when printed out. 5.9 Images Images can be included as character like elements with text flowing around the image, e.g. [Picture missing] Before coming to CERN, Tim worked on, among other [in text version] things, document production and text processing. He developed his first hypertext system, "Enquire", in 1980 for his own use (although unaware of the existence of the term HyperText). With a background in text processing, real-time software and communications, Tim decided that high energy physics needed a networked hypertext system and CERN was an ideal site for the development of wide-area hypertext ideas. Tim started the WorldWideWeb project at CERN in 1989. He wrote the application on the NeXT along with most of the communications software. Internet Draft 15 November 1993 HTML+ Document Format Raggett This example is produced by the following piece of HTML+

Before coming to CERN, Tim worked on, among other things, document production and text processing. He developed his first hypertext system, "Enquire", in 1980 for his own use (although unaware of the existence of the term HyperText). With a background in text processing, real-time software and communications, Tim decided that high energy physics needed a networked hypertext system and CERN was an ideal site for the development of wide-area hypertext ideas. Tim started the WorldWideWeb project at CERN in 1989. He wrote the application on the NeXT along with most of the communications software. The IMG element specifies an image via a URL. The ALIGN=TOP attribute ensures that the top of the image is level with the top of the current text line. You can also use ALIGN=MIDDLE to align the center of the image with that of the current text line, and ALIGN=BOTTOM to align the bottom of the image with the bottom of the current text line. Browsers are not expected to apply text flow retrospectively, so using ALIGN=MIDDLE and ALIGN=BOTTOM may overwrite previous lines of text. If the ALIGN attribute is missing then ALIGN=TOP is assumed. Not all display types can show images. The IMAGE element behaves in the same way as IMG but allows you to include descriptive text, which can be shown on text-only displays: A photo of Tim Berners-Lee Before coming to CERN, Tim worked on, among other things, document production and text processing. etc. On text-only displays, the text within the IMAGE element can be shown in place of the image: [A photo of Tim Berners-Lee] Before coming to CERN, Tim worked on, among other things, document production and text processing. etc. The SEETHRU attribute can be used to designate a chromakey so that the image background matches the document background. This is an experimental feature and the format of the attribute's value has yet to be defined - suggestions are welcomed. Images can be made active in one of three ways o The whole image can be made into a hypertext link o Mouse/Pen clicks on the image can be passed to a WWW server o Shaped hypertext buttons can be overlayed on the image Internet Draft 16 November 1993 HTML+ Document Format Raggett Making the entire image into an iconic hypertext button is simple: Our house In this example, readers can click on a small picture embedded in the document to see a larger version, which would take significantly longer to retrieve. When using images as hypertext links, don't forget to include a textual description. This is needed for the link caption for peo- ple using text-only displays. In some cases, servers can handle mouse clicks or drags on the image. This capability is signalled in the header information returned along with the image data. You can also use the ISMAP attribute. This mechanism and the ability to add shaped buttons are defined in detail in the description of figures. The delay in connecting to the server for each image in turn can be reduced by asking HTTP servers to include images with the HTML+ document as a MIME multipart message (include multipart/mixed with the Accept: header in the request message). 5.10 Change Bars and Document Amendments Change bars are shown for parts of the document designated with the CHANGED element. This can appear anywhere that normal text is allowed (as shown by the %text; entity reference in the DTD): text including some changes The same element is used to designate the start and end of changes, using matched ID and IDREF attribute values. This mechanism avoids syntactic problems that would arise from using a conventional start and end tag pair, as changes to a document can span different levels of the document's formal structure. Additional attributes may be used with the CHANGED element to hold related details, e.g. BY, WHEN, WHY, WHAT. In legal documents and amendments to proposed legislation, there is often the need to show parts of the text as being removed or added to the document. This is commonly shown using strike-through and underlining respectively. The REMOVED and ADDED tags are provided for this purpose:

This bill would require the Legislative Counsel, with the advice of the Joint Rules Committee of the Senate and Assembly, to make available to the public by means of access by way of computer modem the largest nonproprietary, nonprofit cooperative public computer network, specified information concerning bills, the proceedings of the houses and committees of the Legislature, statutory enactments, and the California Constitution. Internet Draft 17 November 1993 HTML+ Document Format Raggett Which might be displayed (on a dumb terminal) as: This bill would require the Legislative Counsel, with the advice of the Joint Rules Committee of the Senate and Assembly, to make available to the public by means of access by way of computer modem the largest nonproprietary, nonprofit cooperative public computer network, specified information concerning bills, the proceedings of the houses and committees of the Legislature, statutory enactments, and the California Constitution. Color enhancements may be used to further distinguish the amendments, e.g. red lines for strike-through. This mechanism is not intended for representing revision histories, which are better served by traditional change control mechanisms. 5.11 Conditional Text It is often quite difficult to phrase the captions for hypertext buttons so that they make sense when printed out. The ONLINE and PRINTED elements can be used to define text which is for use only when read on-line or on the printed page respectively: click herefor more information. Further information can be found in [Higgins 84b]. In many cases, you can find a way of phrasing the reference so that it makes sense both ways. Browsers can help by referencing hypertext links as footnotes when printed out. See the earlier description of the PRINT attribute for the A tag. 5.12 Explicit Line Breaks You can make individual lines explicit with the element, which contains the text of the line in the same way that

contains the text of the paragraph.

22 The Avenue, Harrow, London, NW1 5ER An alternative is the
element which acts as a forced line break.

22 The Avenue
Harrow,
London, NW1 5ER The element is useful when you want to name each line, e.g. . You may also want to disable word wrap for the current paragraph, as in

. Internet Draft 18 November 1993 HTML+ Document Format Raggett 6 Different Paragraph Styles To avoid all text appearing in the same style, HTML+ provides distinct styles for quotes, abstracts, bylines and admonishments. All these elements can contain multiple paragraphs: 6.1 Longer Quotations When you want to include a quotation that extends over more that one paragraph, you should use the QUOTE element. Quoted text should preferably be indented, and rendered using a distinctive font, e.g.

The following is a quotation from the forward by Yuri Rubinsky to "The SGML Handbook" by Charles F. Goldfarb, published by the Clarendon Press, Oxford, 1990. The next five years will see a revolution in computing. Users will no longer have to work at every computer task as if they had no need or ability to share data with all their other computer tasks, they will not need to act as if the computer is simply a replacement for paper, nor will they have to appease computers or software programs that seem to be at war with one another. which might be rendered as: The following is a quotation from the forward by Yuri Rubinsky to "The SGML Handbook" by Charles F. Goldfarb, published by the Clarendon Press, Oxford, 1990. The next five years will see a revolution in computing. Users will no longer have to work at every computer task as if they had no need or ability to share data with all their other computer tasks, they will not need to act as if the computer is simply a replacement for paper, nor will they have to appease computers or software programs that seem to be at war with one another. 6.2 Abstracts The ABSTRACT element can be used to give an overview of a document and typically follows a level one heading. It should be rendered in an easily read font, distinct from normal text, and preferably indented. An example is given in the next section. 6.3 Bylines The BYLINE element is similar to QUOTE and is used for information about the author, e.g. contact details and release date. A common convention is to include a hypertext link to a node with more information about the author. Bylines can occur at the beginning or end of a document, e.g: Internet Draft 19 November 1993 HTML+ Document Format Raggett

HTML+ (Hypertext markup format

A proposed standard for a light weight delivery format for browsing and querying information in a web of globally distributed hypertext accessible over the Internet Editor: Dave Raggett dsr@hplb.hpl.hp.com 6.4 Notes and admonishments The NOTE element is used when you want to draw the readers attention to some point or other. For example: The "partial-window-name" parameter must exactly match the beginning characters of the window name (as it appears on the title bar), including proper case (capital or lower letters) and any punctuation. This is typically rendered as: ---------------------------------------------------------------------- NOTE: The "partial-window-name" parameter must exactly match the beginning characters of the window name (as it appears on the title bar), including proper case (capital or lower letters) and any punctuation. ---------------------------------------------------------------------- The text of the ROLE attribute (if given) is inserted at the start of the note in a bold font and followed by a colon. Typical roles are TIP, NOTE, WARNING and ERROR. The SRC attribute may be used to name a URL or URN as an icon which is displayed in the left margin at the start of the note. An upright hand icon is often used for tips; a warning road sign for warnings and a stop sign for errors. Horizontal rules are drawn automatically to help readers distinguish the note from the surrounding text. You can place horizontal rules in other parts of your document using the
element which can appear anywhere a

element is allowed. 7 Lists There are three kinds of lists, which can be freely nested within one another: o Ordered lists - the list items are automatically numbered o Unordered lists - bulleted or plain styles, in single or multiple columns o Definition lists of terms and associated definitions Internet Draft 20 November 1993 HTML+ Document Format Raggett 7.1 Ordered Lists The OL element is used with LI for each item to represent ordered lists:

  1. Wake up
  2. Get dressed
  3. Have breakfast
  4. Drive to work
which is usually rendered as: 1) Wake up 2) Get dressed 3) Have breakfast 4) Drive to work The COMPACT attribute when present e.g.
    has the effect of reducing inter-item spacing. The numbering style is the responsibility of the browser. Other styles use roman numerals or letters from the alphabet in upper or lower case. One issue for browsers, is how to render ordered lists, nested within a list of the same type. List item text can't include headers, see the DTD in Appendix I for details. 7.2 Bulleted Lists Bulleted lists are represented with the UL and LI elements: which is usually rendered as: o Wake up o Get dressed o Have breakfast o Drive to work Internet Draft 21 November 1993 HTML+ Document Format Raggett The COMPACT attribute when present e.g.