Navigation of Web Pages

Pages on the world wide web may broadly be grouped into three intended uses.  These are:

  1. Gateway pages: These are web pages for which the primary activity is to provide access to other pages on the web.  Such pages are frequently dominated by links.
  2. Query pages: The primary function of these pages is to gather information from user.  Such pages might be subscription pages, registration pages, or even query pages for an on-line database.  Such pages contain forms into which the user of the page inserts information for submission to a remote web server.
  3. Content pages. The primary purpose of content pages is to provide information to the user.  These pages might be on-line books or other publications, catalog entries for an electronic commerce site, or personal web pages describing an individual’s likes and dislikes.


Additionally, the information presented on web pages may be accessed differently depending on whether the content is already known (or suspected), or whether a user is exploring the content of the page without any preconceived notion as to probable content.  These two types of use may be described alternatively as “browsing” and “searching” the content of a page.  The three types of application may all be browsed or searched, depending on the prior knowledge and needs of the user.


The navigation techniques that are used for these types of pages are somewhat different, and a user agent should provide the tools to navigate each type of page to users with disabilities.


Gateway pages


When a user enters a page for the first time, and has no definite goal in mind, s/he should be provided with the ability to explore a web page displayed in a browser.


#16: Sequentially navigate to only link elements (Open)

Historically, gateway pages consist of collections of hyperlinks.  These pages may be formatted as lists or tables of links, or may be formatted to look like content pages by embedding links within pages of text.  In other cases, the links are embedded in a graphic in the form of an image map.  However, in most cases, most of the information content of a site is actually on the linked pages.  Since the functionality of the page is provided through the links, and the other elements on the page are intended to provide context or aesthetic appeal, the user should be able to directly access the functionality of the page, bypassing other elements.

In order to discover the links on such a page, the user agent should provide a facility to move the focus of the user agent from link to link in the logical order of the page via a device independent action.  Because third party assistive technology typically is capable of generating character codes, some character level command should be provided to enact this method of navigation in addition to direct selection via a pointing device.


#3: Should user agents be able recognize markup for navigation bars

As the web evolves, pages are including navigation bars as alternatives to lists of text links.  Navigation bars appear as collections of buttons or text which provide links to other pages, and may have added behaviors such as changing size or color when the mouse pointer hovers over them.  The document markup for such navigation bars may be substantially different from that of traditional links, but in order to provide equivalent functionality for users with disabilities, navigation bars should be accessible both via direct selection with a pointing device and via character level commands.


When a web page is commonly used by an individual as a gateway, and the user has a significant familiarity with the content of the page, it may be more efficient to jump directly to a desired link.  If the user enters a gateway page for the first time, but with a definite goal in mind, s/he may wish to quickly discover if the page contains a link to a specific destination.  Finally, a user who is exploring a page may wish to distinguish between links that have been visited, and those that have not.

#21: Search for link based on its text content (Open)

A user agent should provide the ability to search for a web page based on the text content of the link.  For example, if the user were looking for information on Koala bears, it would be useful to be able to search for links containing the term Koala.  This will allow the user to move directly to a link on a page, or to determine that the page does not contain such a link.

#38: Search for a link based on its attribute value (Open)

When a user is exploring the web, and returns to a gateway page, s/he may wish to either return to a linked page that had previously been visited, or to move directly to unvisited links.  In either case, the user agent should be able to search for links based on their attributes.  Additionally, because the text of a link may not be identical with the content of a link, it may be desirable to search within the text of a URL, in addition to the content of a link.  For example, the link to might contain text like “cute, cuddly bears with vile tempers.”  Searching for the text “Koala” would not find this link.  Searching within the attribute would.

Query Pages

Query pages allow web sites to obtain information from users.  This information might be used to place orders from an e-commerce site, to subscribe to a newsletter or magazine, or to request information from an online database.  In each case, the goal is to obtain information from the user of the page.  Such pages may have significant explanatory text around the data collection elements, which is helpful to the novice user, but unnecessary by the experienced user.  Because a user with a disability may not be able to scroll directly to elements of interest and directly select their content with a pointing device, the user agent should provide equivalent functionality.


#22: Sequentially navigate between forms in a document (Open)

A complex query site may have multiple forms or equivalent embedded objects to support a range of possible query types.  A library site might have separate forms for “Search by Author,” “Search by Title,” and “Search by Topic.”  An able-bodied user can scan a page, and use a pointing device to select the first element of the desired query form. Each form may be composed of many elements, and sequential navigation of form elements on a page would be a substantial burden to a user if this were the only way to navigate to a form that was several forms down a page.

To provide equivalent functionality for individuals with disabilities, a user agent should provide a means to move through the page by form level markup.  This would allow the person with a disability to jump directly to a form, determine if the form met the desired intent, and, if not, jump directly to the next form, without the need to move through each element of the form.

#17: Sequentially navigate to only form controls in a document (Open)

Once the user has located the desired form, it is essential that s/he be able to move from form control to form control within the form, in order to provide the functionality of the form to the user who does not have access to a pointing device.



#24: Search for a form control based on its attribute values (i.e. label or control type) (Open)

The user who is visiting the on-line library, and is searching for books by a favorite author may wish to jump directly to a form which requests information about authors.  The ability to search a page by form control attributes would provide this functionality. 

#23: Search for a form control based on text content (Open)

It is sometimes useful to search for a form control based not on its label, but on its content.  For example, some web sites evaluate data entry at the time the data is submitted, and will not accept data that is in the wrong format.  If the user has inadvertently made a typographical error in entering his/her address, it would be desirable to be able to jump directly to this error to correct it.  However, the form control for the address might be labeled “Address,” “Address1,” or even “Street.”  Because the labels are inconsistent, the user may not be able to directly find the information that must be corrected.  However, since the user knows that the item contains “Pine St.”, being able to search for form controls based on content would allow immediate navigation to the data to be corrected, in spite of inconsistent labeling of the control.


Content Pages

While many pages are used to solicit information, or to guide users to other pages, one primary reason for browsing the World Wide Web is to obtain information from it.  A user desiring content from the web needs to be able to move through the content of the page in blocks of content that allow access to the information contained on the page.  Able-bodied users are able to read text on the screen, and scroll quickly through a document, visually scanning for content of interest.  In some cases, the user is actively seeking content on a specific topic.  In others, the user is simply looking for content that will peek his/her interest, and provide entertainment.   User agents should support both types of examination of web pages.


#20: Sequentially navigate header elements (Open)

A well-formed document may be structured with header elements describing a section of content, followed by that content.  The headers might form the titles of chapters of a book, or the sections of a professional document.  One method of navigating a long document in search of content would be to move from header to header through the document.  Since, headers are, by their nature, hierarchical, a header navigation technique should allow navigation by headers of different levels.  The user should be able to move from <H1> element to <H1> element, and then move to lower level elements within a document.

#18: Sequentially navigate to only elements with long descriptions (longdesc attribute or OBJECT content) (Open)

The user may wish to obtain information about the embedded objects within a page, by moving from descriptive element to descriptive element through a page.  In this way, the visually impaired user, for example, could quickly get a sense of the graphical elements on a page that are absorbed peripherally by the sighted user.


The most important, but frequently overlooked aspect of page browsing is navigation of the text of a web-based document.  Sighted users navigate pages by reading them from the screen, and scrolling through the document using a pointing device.  The inability to visually access a page, or physically access a pointing device can substantially limit access to the content of pages by individuals with disabilities.  In order to provide equivalent functionality, a user agent should provide the ability to shift the point of regard through a document encompassing the content in meaningful segments.  While the page-down function of a browser allows movement through a document in sections, the sections are determined by the window of the browser rather than the content of the document.  After shifting the view port of a browser, the text displayed may begin in the middle of a sentence, and not be meaningful outside of its context.  To provide equivalent access for individuals with visual deficits, the user agent should allow changing the point of regard by paragraphs, as well as by larger block structures.


When entering a page that has been identified as containing specific information, the user may have to do significant scrolling to find that information.  It is, therefore, essential that a user agent allow the user to search for specific text within a page.  The browser should provide the ability to search for the next occurrence of a segment of text without retyping the search key.


Global Issues


#15: Sequentially navigate between active elements (Resolved)

Many web pages include active elements that can provide functionality based on user actions.  These include features activated by “mouseover” and “mouseleave” events, features activated by clicking on an object within a page, and other scripted functionality.   Scripts may be attached to arbitrary components of a page, not just to links and form controls.  In order to provide equivalent access to users with disabilities, a user agent should provide a means of locating and activating embedded active elements.  This functionality would require moving the mouse pointer (or other point of regard indicator) over active elements, and simulating mouse clicks in a device independent manner.


#27: Move to the next element in the document tree as defined by DOM (Open)

#28: Move to the child level element of the current element in the document tree (Open)

#29: Move to the next (or previous) sibling element in the document tree (Open)

#30: Move to the parent element of the current element in the document tree (Open)

One strategy for navigating a document is to allow the user to “walk the document tree.”  In this strategy, the user is able to move from the root element of a tree throughout its structure.  Such functionality requires that the user agent provide a means of moving from any element to its first decendent, to its prior or next sibling, and to its parent.  In a fully functional implementation, a user would be able to move from an element to its parent, and then move directly back to the starting element, regardless of where it falls in the sibling hierarchy. 

Walking the document tree, by its nature, provides much of the functionality of navigation of a document described in earlier sections, but has the disadvantage of requiring the end user to understand the concept of the document tree, and the structure of an arbitrary document in order to predict the action of any given command.

#11: Move to the next element with the same attributes and element type (Open)

Examining the degrees of functionality required for equivalent access shows that, if each of the types of navigation were provided by separate commands, a user would have a significant cognitive task in learning to navigate the browser.  Having individual commands for navigation by links, by link attributes, by navigation bars, by forms, by form elements, and by headers and paragraphs would require the user to remember each type of command to use the provided functionality.  This would significantly disadvantage users with limited cognition.

As an alternative strategy, a user agent might be designed to allow the user to “find the next thing like this one.”  Such a browser would have to implement a point of regard indicator that moved from block element to block element under the control of the user.  When the user found the type of element that seemed to be significant to his or her purposes, a command could be issued that would “find the next element like this one.  Such a command would be sensitive to links, visited links, forms, form controls, tables, table cells, headers and paragraphs.  It would also sensitive to attributes such as font characteristics.  In this way, even though the author of a page uses font attributes to simulate headers, a user agent would be able to simulate moving through headers by matching the font attributes selected.

The most significant advantage of this strategy is that it requires minimal understanding of the document structure and command structure by the user.  When the user finds a document section that seems to contain the type of information of interest, a single command can move to the next similar element, regardless of the nature of the element under consideration.  A second command would find the previous element, allowing two-way navigation throughout the document.


#26: Search for an element based on its text content (Open)

Searching a document’s contents should be possible by either its text content, or, given the functionality suggested above, by the attributes of the content.  When a user enters a web page that, according to their web search utility, contains information on Koala bears, s/he may wish to locate the word Koala on the page.  Since the term may be located many screens down a document, such search facility adds significantly to the usability of a user agent.

Many authors use in-line markup to indicate elements of interest.  Key words in a document may be formatted as <strong> to indicate their importance.  Key paragraphs may be formatted in a different font, or with different indenting. These techniques allow the visual user to quickly identify significant ideas while scanning through a document.

To provide equivalent access to users with visual impairments, a user agent should provide the ability to search within a document based on the attributes of the text as well as the content of text. A user might seek to find elements with <strong> formatting, or elements with a specific font.