Request for Comments: XXXX (cid:9)
`
`David Raggett (Hewlett Packard)
`23rd July 1993
`
`HTML+ (Hypertext markup language) (cid:9)
`
`,
`
`A proposed standard for a light weight presentation
`independent delivery format for browsing and
`querying information across the Internet
`
`Status of this Memo
`This document is a proposal for an Internet Draft, and specifies the HTML+ wide-area hypertext
`document format, with a view to requesting discussion' and suggestions for improvements.
`Distribution of this memo is unlimited.
`
`Abstract
`HTML+ is a simple SGML based format for wide-area hypertext documents, for use within the World
`Wide Web. Unlike desktop publishing formats, HTML+ captures the logical intent of authors. This
`simplifies the task of writing documents, and permits them to be effectively rendered on a wide range
`of display types as well as the printed page.
`
`HTML+ represents a substantial improvement over the existing format: HTML, offering nested lists,
`figures, embedded data in foreign formats for equations etc, tables with support for titles and column
`headings, change bars, entry forms for querying and updating information sources and for use as
`questionaires for mailing. This document specifies the HTML+ format with guidelines on how it
`should be rendered by browsers.
`
`Introduction
`The World Wide Web is a wide area client-server architecture for retrieving hypermedia documents across the
`Internet. It also supports a means for searching remote information sources;for example bibliographies, phone
`directories and instruction manuals. There are three main ingredients:
`
`a) Universal naming scheme for documents. The universal resource location 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 working
`groups of the IETF. A network protocol will allow universal resource numbers (URNs) to be
`resolved to the URL for the nearest available copy.
`
`b) Use of available protocols for retrieving documents over the network, including FTP, NNTP,
`WAIS, Gopher, and HTTP. The latter is designed specifically for use with the World Wide Web,
`and combines efficiency with an ability to flexibly exchange information between clients and
`servers.
`
`c) A document format supporting hypertext links based on URLs and URNs which can specify
`documents anywhere in the Internet. HTML+ is designed for rendering on a wide variety of
`different display types and platforms.
`
`Information browsers can display information in a wide variety of formats, e.g. plain text, rich text in the
`HTML+ format, images in the GIF and JPEG formats, MPEG movies, and MIME documents. The hypertext
`format has a special significance as it allows users to navigate from one document to the next at the click of a
`button. It provides the basis for menus, cross references, either within a document or to other documents,
`
`'Please mail comments to the author dsr@hplb .'hpl . hp . corn, or to the WWW discussion group:
`www-talk@nxocOl.cern.ch
`
`Ex. 1013 - Page 1 of 34
`
`Groupon, Inc.
`Exhibit 1013
`
`

`
`perhaps on the other side of the world. It also provides a means of building larger scale collections of
`documents that act as journals, books or encyclopedias. The format is also intended to act as a building block
`for creating wide area groupware applications.
`
`HTML+ follows on from an earlier standard - HTML, see [Berners-Lee 93a], which has been widely used as
`the basis for hypertext documents in the World Wide Web. The new format grew out of experience with
`HTML, culminating in the desire to add new features, e.g. inline images, tables, and form fields for greater
`flexibility in querying remote information sources. This document specifies the HTML+ format and suggests
`ways in which browsers can choose to render it on a variety of different display types.
`
`2. (cid:9) HTML+ and SGML
`HTML+ itself is based on the Standard General Markup Language (SGML), 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 the document should 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.
`
`Working groups in ISO have recently produced a range of SGML DTDs for documents, e.g. ISO 12083 defines
`DTDs for books and ISO 10744, which defines the HyTime standard for hypermedia/time-based documents.
`These standards are large and complex, and perhaps best suited as interchange standards that facilitate
`conversion between proprietary document formats. By contrast, HTML+ provides a lightweight delivery
`format that can be rendered by relatively simple browsers, and which has grown out of two years practical
`experience with wide-area hypertext information systems in the Internet community.
`
`HTML+ and HyTime
`
`zSi
`
`rj
`
`The HyTime standard provides a rich range of architectural forms, but is not aimed at run-time efficiency.
`Suggestions have been made as to how the HTML DTD could be adapted to comply with HyTime's clink
`architectural form [Kimber 93]. This would necessitate documents declaring links as external entities and the
`use of local names in link definitions, but in the absence of any immediate benefit, there has been little
`enthusiasm for this within the World Wide Web community. Instead, it is believed that a straightforward filter
`program should be used to map HTML and HTML+ documents into a format which is strictly compliant with
`HyTime, when this becomes appropriate.
`
`A simple example of HTML+
`
`The following is a simple example of an HTML+ document,which illustrates the basic ideas involved in
`SGML.
`
`<title>A Simple HTML+ Document</title>
`<hi id="a1">This is a level one header</hl>
`
`<p> This is some normal text whiCh will wrap at the window margin. You
`can emphasise <em>parts of the text</em> if you wish. </p>
`
`<p> This is a new paragraph. Notice that unlike title and header tags,
`the matching end tag is optional.
`
`The text of the document includes tags which are enclosed in <angle brackets>. Many tags have matching end
`tags for which the tag name is preceded by the "I" 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 parameters,
`e.g. the "id" attribute in the header tag, which is used to define potential destinations for hypertext jumps.
`
`Unlike most document formats, SGML leaves out the-processing instructions that determine the precise
`appearence of the document, for example the font name 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), and so can avoid problems with different page sizes or missing fonts.
`
`2
`
`Ex. 1013 - Page 2 of 34
`
`

`
`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.
`
`Practical experience has shown that people often make mistakes when they have to type in the markup for
`themselves. As a result, most browsers are tolerant of bad markup. This problem is being minimised by
`keeping the format as simple as possible and encouraging the development of WYSIWYG editors.
`
`The HTML+ Document Format
`
`The following sections go through the various features of the format with suggestions as to how browsers
`should render them. The DTD for HTML+ is given in Appendix I.
`Parsing HTML+ Documents
`By default, HTML+ documents are made up of 8-bit characters in the ISO 8859 Latin-1 character set. In
`future, 16 bit character sets may be used to cover a wider range of languages. The HTTP network protocol uses
`the MIME standard (RFC 1341) to specify the document type and the character set. It is assumed that the
`chosen character set includes the printable 7 bit US ASCII characters as a subset.
`
`The DTD specifies the syntax of the document structure, in particular, which tags are permitted in any given
`context. Certain tags are only permitted at the start of the document. Tags and attribute names are case
`insensitive, thus <TITLE> is equivalent to <title>. Minimisation is forbidden to avoid problems with parsing
`unknown tags.
`
`In general, SGML entity definitions are used to represent characters which would otherwise be confused with
`markup elements:
`
`is represented by (cid:9)
`
`is represented by (cid:9)
`
`is represented by (cid:9)
`
`&amp ;
`
`sc1 t ;
`
`&gt ;
`
`Such entity definitions should be used in all places except within attribute values for tags (tag names and
`attribute names cannot contain these particular characters). Entity definitions can also be used for special
`characters, e.g. "&eacute;" for a small e with an accute accent. The full list is given in Appendix II. Additional
`entities may be defined within documents using the SGML entity declaration tag !ENTITY, e.g.
`
`< !ENTITY sgml "Standardised General Markup Language " >
`
`The browser will then insert the full form whenever it comes across "&sgml;".
`
`Repeated white space characters such as space, tab, carriage return, line feed and form feed are ignored except
`within preformatted text, i.e. it doesn't matter which white space characters you use or how many of them you
`put between words, or before or after markup elements, the effect is the same as a single space character.
`
`It is strongly recommended that HTML+ documents start with the following external identifier, indicating that
`the document conforms to the HTML+ DTD. This will ensure that other SGML parsers can process HTML+
`documents, without needing to include the DTD with each document.
`<!DOCTYPE htmlplus PUBLIC "-//Internet/RFC xxxx//EN">
`
`HTML+ departs slightly from pure presentation independence by allowing authors to specify rendering hints,
`e.g. to use a bold font for a given type of emphasis. This step was taken to give authors greater control over the
`final appearence, and is based upon practical experience with the earlier HTML format. In addition, attribute
`values are used to distinguish different subcategories of markup, rather than adding extra tags. New logical
`categories of emphasis etc. can be added in future without needing to change existing browsers. These
`decisions have made it practical to restrict HTML+ to a very small set of tags.
`Backwards Compatibility with HTML
`The format is designed to be largely compatible with the earlier format HTML, and it is recommended that
`HTML+ browsers continue support for the few tags which have been dropped. This will avoid problems for
`the large numbers of HTML documents without the DOCTYPE declaration. Suggestions on how to map
`HTML elements to HTML+ are given in Appendix III.
`
`3
`
`Ex. 1013 - Page 3 of 34
`
`

`
`Normal Text
`
`This is generally shown with a serif font and wraps on the right window margin. It can include:
`
`101 (cid:9) Entity references, e.g. "&gt ; " and " &eacut e ; "
`
`01 (cid:9) Significant Line breaks (the BR tag)
`
`1:1 Hypertext links - the A tag
`
`101 (cid:9)
`
`Inlined graphics or icons - the IMG tag
`
`01 (cid:9) Various styles of logical emphasis - the EM tag
`
`CI Embedded data in an external format, e.g. TeX equations - the EMBED tag
`
`101 Input fields for forms - the INPUT tag
`Line breaks and <BR>
`Line breaks have a semantic significance in some contexts, e.g. the lines of a poem or a postal address. This
`tag causes the renderer to start a new line at the current left margin setting. There is no corresponding end tag.
`The BR tag is empty, that is to say, it doesn't act as a container around other text or markup.
`Hypertext Links
`When the user clicks on a hypertext link in the document, the current document is replaced by the one
`referenced by the link. Links can be made to a wide range of document types, based on the URL2 and URNS
`notations. Some document types permit links to be made to specific sections within a document4. The syntax
`for links within the same document or to documents in the same directory is particularly simple:
`Links are defined with the <a href="#z1">A tag</a>. HTML+ supports a
`number of <a href="links.html">different link types</a>.
`
`In a browser this might look like:
`Links are defined with the,A tag. HTML+ supports a number of different
`link types.
`
`The first link is to an anchor named "zl" in the current document. The second is to a file named "links.html" in
`the same directory as the current document. The caption for the link is the text between the start and end tags.
`The value for the HREF attribute defines the destination point, and can be abbreviated in certain cases. If
`practical, word the caption in such a way that continues to make sense when the document is printed out. The
`link should be shown in a clearly recognisable way, e.g. as a raised button, or with underlined text in a
`particular color. For displays without pointing devices, it is suggested that a reference number is given in
`square brackets, which can then be typed by the user.
`
`A more general discussion of hypertext links and their treatment in HTML+ is presented in a later section.
`Inlined Graphics or Icons
`These are treated like characters and inserted as part of the text, e.g.
`This line has a egyptian hieroglyph at the end of the
`line. <img src="ankh.tiff">
`
`The URL notation is used to name the source of the graphics data. The align attribute can be used to control
`the vertical position of the image relative to the current text line in which the IMG element is placed. Use a
`value of "top", "middle" or "bottom" to align the top, middle or bottom of the image with the current text line.
`
`2The notation for universal resource locators is defined in [Berners-Lee 93b].
`
`3The notation for universal resource numbers and the protocol for resolving them to the nearest available copy
`is currently under study by the IETF URN working group.
`
`4At the time this document was written, such links were restricted to named anchors within HTML and
`HTML+ documents
`
`4
`
`Ex. 1013 - Page 4 of 34
`
`

`
`The seethru attribute allows authors to include a chromakey, i.e. a colour that designates portions of the image
`to be left unpainted so that the background shows through. The format for this attribute's value is dependent on
`the type of graphics data, and has yet to be defined.
`
`Note that you can create simple iconic buttons, e.g.
`
`<a href="bigpic.gif"><img src="littlepic.tiff"></a>
`
`If the user clicks anywhere on the image, this will cause the browser to retrieve its bigger version. This
`approach allows users to preview images which may take significant time to download. Note that there is little
`additional penalty for displaying the same image at multiple points in the document. The ismap attribute is
`provided for backwards compatibility with HTML. When present the browser will send all mouse clicks and
`drags on the image, to the server.This mechanism is explained in more detail for the FIG tag.
`
`Sophistocated HTML+ editors should allow authors to modify images using an external editor. Larger images
`should be specified with the FIG tag.which provides support for flowing text around figures, along with
`captions, overlays and active areas.
`Various Styles of Emphasis5
`
`This allows you to emphasise a portion of the text. The simplest approach is:
`
`<em>default emphasis, usually shown in an italic font</em>
`
`The logical role of emphasis denotes the semantic significance, e.g. a citation, or text to be input by a user for
`a computer program.The physical style of emphasis controls its appearence. Note that EM elements can
`include inlined graphics.
`
`Logical Role of Emphasis
`
`It is strongly recommended that the logical role of the emphasis is given with the role attribute, e.g.
`<em role="cite">a citatiOn</em> •
`
`Providing a logical role allows browsers to apply differing rendering styles according to the role, but more
`importantly, it allows indexes to be constructed automatically, e.g. the list of bibliographic references in a
`technical report. These can be used for searching through collections of documents according to semantic keys
`giving better focussed searches compared with full text indexes .
`
`The list of recommended roles are as follows: (cid:9)
`
`(this can be given in upper or lower case)
`
`For references to other works:
`
`cite (cid:9)
`pub (cid:9)
`author (cid:9)
`editor (cid:9)
`title (cid:9)
`credits (cid:9)
`copyright (cid:9)
`isbn (cid:9)
`acronym (cid:9)
`abbrev (cid:9)
`
`a reference to a related work
`a publication containing a referenced work
`an author of a referenced work
`an editor of a referenced work
`the title of a referenced work
`e.g. the rights owner of a photograph
`the holder of the copyright
`for ISBN numbers
`for acronyms like "NATO" and "US"
`for abbreviations
`
`For annotations:
`footnote (cid:9)
`margin (cid:9)
`For computer instruction manuals:
`
`shown as footnote or pop-up
`shown as margin note or pop-up
`
`dfn (cid:9)
`
`defining instance of a term
`
`5The name EM was chosen in preference to EMPH because it alloWs existing HTML browsers to show all
`HTML+ emphasis in italics. It also allows HTML+ browsers to correctly process the common case for
`emphasis in HTML documents.
`
`5
`
`Ex. 1013 - Page 5 of 34
`
`

`
`kbd
`cmd
`arg (cid:9)
`var (cid:9)
`ins (cid:9)
`opt
`code
`samp
`
`something a user would have to type
`command name, e.g. "chmod"
`command arguments, e.g. "-T"
`named place holder, e.g. "filename"
`an instanced of a named printer, directory or file etc.
`an option of some kind
`an example of code (shown with a fixed pitch font)
`a sequence of literal characters
`
`On dumb terminals annotations should be shown in round brackets. Margin notes should be right aligned, and
`may include graphics via the IMG tag. The set of recommended roles will be kept by the HTML+ registration
`authority.
`
`Physical Styles
`
`The appearence can be modified by adding optional rendenng hints from the list:
`bold text
`italic text
`underlined text
`superscript text
`subscript text '
`type writer font (courier)
`sans serif font (helvetica)
`serif font (times roman)
`
`<em b>
`<em i>
`<em u> (cid:9)
`<em sup> (cid:9)
`<em sub> (cid:9)
`<em t t>
`<em hv> (cid:9)
`<em tr> (cid:9)
`These hints can be combined, e.g.
`
`<em b i> for bold italic text </em>
`
`Note that these are only hints and may be ignored by browsers. Indeed, arbitrary combinations will present
`difficulties for most browsers. If the display is limited to a single font, colour or underlining can be used, but
`should be clearly differentiated from hypertext links and headers. Dumb terminals can use email conventions,
`e.g. switching to all capitals, or delimiting with the * or _ characters. Subscript and superscript text should be
`shown in a smaller point size, vertically offset as appropriate.
`
`Browsers may choose to simplify or ignore hints, but should aim to do so in a consistent manner. At the
`simplest level, browsers can ignore the attributes and render all emphasis in the same style.
`
`,Nested Emphasis
`
`Emphasis can be nested as in:
`<em b>bold text, and <em i>bold italic text</em></em>
`
`Nested emphasis is better suited for grouping logical roles together, for instance, you could use EM to
`separately tag author, title, and publication, and then wrap these up as a citation. Without this, indexing
`programs will have difficulty in grouping markup into the correct references.
`Horizontal Rule
`The <11R> tag may be used to draw a horizontal rule to separate text sections. It can be rendered as a simple
`line across the middle section of the window/paper or similar decoration.
`Embedded data in an external format
`The EMBED tag provides a simple form of object level embedding. This is very convenient for mathematical
`equations and simple drawings. It allows authors to continue to use familiar standards, such as TeX and eqn.
`Images and complex drawings are better specified using the FIG or IMG elements. The type attribute specifies
`a registered MIME content type and is used by the browser to identify the appropriate shared library or
`external filter to use to render the embedded data, e.g. by returning a pixmap. It should be possible to add
`support for new formats without having to change the browser's code, e.g. through using a common calling
`mechanism and name binding scheme. Sophistocated browsers can link to external editors for creating or
`revising embedded data. Arbitrary 8-bit data is allowed, but &, < and > must be replaced by their SGML entity
`definitions. For example <embed type="application/eqn"> 2 pi int sin (omega t)dt </embed> gives
`24 sin (v)cit
`
`6
`
`Ex. 1013 - Page 6 of 34
`
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`(cid:9)
`

`
`Input Fields for Forms
`Input fields can be arranged with considerable freedom, as part of normal paragraphs, preformatted text, lists
`or tables. Examples of how to do this are given later on in the section describing the FORM tag. The INPUT
`tag has the following attributes:
`
`name (cid:9)
`
`type (cid:9)
`
`size (cid:9)
`
`value (cid:9)
`
`Used to name this input field, e.g. name= "phone number" (required attribute).
`
`Defines the type of data the field accepts (the type name is insensitive to upper/lower case).
`If missing, the field is assumed to be a free text field.
`
`Specifies the size/precision of the input field according to its type, see below (optional).
`
`The initial value for the field, or the value when checked for checkboxes and radio buttons
`(optional, except for radio buttons).
`
`checked When present, this attribute indicates that a checkbox or radio button is selected.
`
`disabled When present, this attribute indicates that this field is temporarily disabled. Browsers should
`show this by greying out or via a similar visual clue. Users are unable to set the focus to
`disabled fields, or change their values.
`
`error (cid:9)
`
`When present, this attribute indicates that the current value for this field is in error in some
`way, e.g. because it violates some consistency constraints. Browsers should indicate this by a
`change to the shape and colour (red) of the field's border. This should be accompanied by an
`error message and a beep.
`
`The following types of field should be supported: (cid:9)
`
`(in either upper or lower case)
`
`text
`
`url
`
`int (cid:9)
`
`float (cid:9)
`
`date (cid:9)
`
`checkbox (cid:9)
`
`radio (cid:9)
`
`Single or multi-line text entry fields. Use the size attribute to specify the width and
`height in characters, e.g. size="24" or size="32x4".
`
`For fields which expect document references as URL or URNs.
`
`For entering integer numbers, the maximum number of digits may be given with the
`size attribute, e.g. size=3 for a 3 digit number6.
`
`For fields restricted to floating point numbers.
`
`Restricted to a recognised date format.
`
`Use these for simple boolean attributes, or for attributes which can take multiple
`values at the same time from some set of alternatives (for fields with the same
`name).
`
`Use these for attributes which can take a single value from a set of alternatives
`(groups input fields with the same name).
`
`For the purposes of sending the contents of a form to a server, as part of a query, the input fields are mapped to
`a list of properties. In most cases the name and current value are used to define a property/value pair for each
`field. Radio buttons and check boxes are left out of the list if they are unselected. This ensures that only the
`selected radio button yields a property/value pair. By missing out the value attribute for check boxes, these
`fields will map to a simple (value-less) property. The representation of property lists is defined as part of the
`HTTP protocol.
`
`Browsers can choose to notify the server whenever a field is changed (i.e. when a field looses the focus and its
`contents have changed) or wait until the form is completed. This choice will depend on network latency.
`
`Drop down or "combo" style selection lists may be added in a future revision to this standard.
`
`ag=
`
`6Perhaps the syntax should permit integer ranges, e.g. size="1 to 6", in which case a more appropriate name
`for the attribute than size would be desirable.
`
`7
`
`Ex. 1013 - Page 7 of 34
`
`(cid:9)
`(cid:9)
`

`
`Headers and Titles
`The title tag is generally used to define the window banner when viewing a particular document, e.g.
`
`<title>Reference Guide to HTML+</title>
`
`This element should appear at the start of the document. There are six levels of headers, H1 to H6, with H1 the
`most important, and H6 the least. A common convention is to begin the body of the document with a level one
`header. e.g.
`
`<hl>Introduction to HTML+</h1>
`
`Header names should be appropriate to the following section of the document, while the document 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. Browsers should render headers with a line break before and after
`the header text. A common convention for headers is to use a sans serif font, e.g. Helvetica, with a smaller
`point sizes for less significant headers, and a serif font, e.g. Times Roman, for normal text.
`
`Headers can include an identifier, unique to the current document, for use as destinations of hypertext links,
`e.g.
`
`<hi id="intro">Introduction to HTML+</hi>
`
`This allows authors to make 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 may
`automatically generate the identifiers. In this case, they should also provide a point and click mechanism for
`defining links, so that authors don't need to deal explicitly with the identifiers.
`
`The attribute "margin" when present acts as a hint to the browser to insert the header into the margin and
`causes the following text to be vertically aligned with the start of the margin header. By convention, margin
`headers are left justified, e.g.
`
`<h4 margin> Deleting the Curve </h4>
`
`The Delete command allows you to delete any selected symbol or text
`block.
`
`Note that headers don't act as containers for the subsequent text. You can group the header and text with the
`GROUP tag, see later for details.
`
`Indexing
`A good index plays an important role in helping you find your way to the material you need. It allows you to
`type in one or more keywords to see a list of matching topics. Alternatively you can browse through the index
`and take advantage of serendipity. This also allows you to gain a feeling for the limits of what is covered. The
`two approaches can be combined, when the characters typed act dynamically to control the viewing position
`within the index.
`
`Typically each keyword entry in the index is associated with one or more topics. This notion of guiding the
`user is absent from full text indexes like WAIS, where users are given very little help in choosing the
`keywords to search on. Generating a conventional index for a document is a skilled task, and HTML+ allows
`authors to include directives for creating an index. These directives can be included with document titles,
`headers and emphasis etc. using the index attribute. This allows each such element to be included in one or
`more entries in the index, under primary or secondary keys, e.g.
`
`<h3 id="z23" index="Radiation damage/shielding from as difficult">Radiation shielding</h3>
`
`8
`
`Ex. 1013 - Page 8 of 34
`
`

`
`This resulting index looks like:7
`
`Radiation damage
`classical target theory
`dominance of
`in molecular mills
`shielding from as difficult
`simple lifetime model
`track-structure lifetime model
`Radicals
`and so on.
`
`Where each entry is a hypertext link to the associated anchor. The index attribute can specify multiple entries,
`each separated with the ";" character. The optional secondary key (shielding from as difficult) is introduced by
`the "I" character. Secondary keys are useful when the primary key occurs more than once. To, allow for future
`extension, primary keys should not start with the "#" character. This prefix is being reserved to designate
`indirect index entries. Use "V", "\;", "\#" and "\\" to escape "I", ";", "#" and "1" respectively.
`
`Paragraphs and Preformatted Text
`HTML+ includes support for paragraphs and preformattted or verbatim text.
`
`Defining Paragraphs with <P>
`The P, tag is used to define paragraphs. Unlike many other tags, the end tag is optional. Note, that unlike
`HTML,the tag acts as a container for the text of the paragraph. This allows paragraphs to act as hypertext
`anchors. The end of the paragraph is implied by finding markup elements which are not permitted as part of a
`paragraph.
`
`The following attributes may be used:
`
`id (cid:9)
`
`role (cid:9)
`align (cid:9)
`
`An identifier, unique to this document, which can be used as a destination in a hypertext link.
`
`The role of the paragraph, see the folloWing list for supported types.
`
`A rendering hint to the browser to justify lines. The supported values should be:
`align="lef t", align="center", aligia="right" and align=" flush". This
`is useful for single line paragraphs or when the lines are made explicit with the <BR> tag.
`
`indent (cid:9)
`
`When present, this hint suggests that the left and right margins are indented by an amount
`dependent on the browser, e.g. about 4 character widths.
`
`The role attribute is used to indicate the logical role of the paragraph, e.g. a stanza in a poem or a cautionary
`note in a computer manual. Browsers may apply particular rendering styles to certain roles. The role name is
`case insensitive.
`
`The following roles are recommended: (cid:9)
`
`(in upper or lower case)
`
`quote (cid:9)
`
`byline (cid:9)
`
`note (cid:9)
`
`caution (cid:9)
`
`error (cid:9)
`
`A paragraph quoted directly from some other work. Browsers could indent the paragraph and
`maybe use a different font.
`
`Information about the author of the document, e.g contact details. This could be displayed in
`a different font, and perhaps right aligned.
`
`Advisory note in an instruction manual. The browser could display a hand icon in the
`margin.
`
`Cautionary note. The browser could display an warning road sign in the margin.
`
`A note describing error conditions: The browser could indicate the importance of the note by
`displaying a stop sign in the margin.
`
`7Taken from K. Eric Drexlers's "Nanosystems, Molecular Machinery, Manufacturing and Computation".
`
`9
`
`Ex. 1013 - Page 9 of 34
`
`

`
`An example of a paragraph element:
`<p role="note"> If you accidentally delete a symbol other than the red
`circle, immediately press ALT+BKSP to choose the undo command, and
`then select the red circle and delete it again.
`
`Paragraphs can be rendered by indenting the first line, or by leaving a vertical gap, for example, half the
`current line spacing. When using the latter style, browsers should take care to avoid inserting this vertical gap
`when the paragraph element immediately follows a header. This rule ensures that authors can tag paragraphs
`directly following a header without causing unwanted extra space to appear before the start of the text.
`
`Preformatted Text with <PRE>
`
`This is generally shown in a fixed pitch font and preserves the original spaces and line breaks. The horizontal
`tab character is deprecated, but should be interpreted as a move to the next tab setting, at every eighth column.
`Preformatted text is useful for including plain ASCII text, e.g. program listings and email messages. A number
`of tags can be included within preformatted text, e.g. hypertext links using the A tag, emphasis, inline images
`and input fields. The following optional attributes can be used:
`
`id (cid:9)
`
`role (cid:9)
`
`tr (cid:9)
`
`hv (cid:9)
`
`width (cid:9)
`
`An identifier, unique to this document, which can be used as a destination in a hypertext link.
`Note that the paragraph tag acts as a container for the paragraph.
`
`The role of the element.
`
`Use