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A format for describing syntax which is accessible to blind users

IP.com Disclosure Number: IPCOM000015396D
Original Publication Date: 2001-Dec-16
Included in the Prior Art Database: 2003-Jun-20
Document File: 4 page(s) / 54K

Publishing Venue

IBM

Abstract

Disclosed is a method for rendering syntax diagrams in a form which is accessible to blind people using a screen reader. We first describe the new format which we have called "dotted decimal" and then describe why blind people find the dotted decimal notation easier to use than the alternatives.

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A format for describing syntax which is accessible to blind users

Disclosed is a method for rendering syntax diagrams in a form which is accessible to blind people using a screen reader. We first describe the new format which we have called "dotted decimal" and then describe why blind people find the dotted decimal notation easier to use than the alternatives.

    Software and its associated information are made accessible to blind users through use of a piece of assistive technology called a "screen reader". A screen reader reads out the contents of a screen so that a blind user can hear what is on the screen. There are a number of different screen readers available commercially.

    There are a number of factors that are important to take into account when designing software or information that may be used with a screen reader. For example, some screen readers do not provide the user with formatting information such as bold . Additionally, tables and frames in HTML are handled to a different level of sophistication by different screen readers. Furthermore, no commercially available screen readers provide easy access to horizontal positioning. Also, mixing words (with punctuation) often causes problems for screen reader users.

    The railroad syntax diagram is now the standard way of describing syntax in manuals. It is a visual representation which relies on the horizontal and vertical positioning of syntax elements to convey meaning. It uses horizontal lines to connect successive syntax elements, and vertical lines to connect alternative syntax elements. A horizontal line can thus contain syntax elements from different vertical stacks. This is visually obvious, but is inaccessible by a blind person using a screen reader. The blind person would have to ask their screen reader to speak the row and column PEL (picture element) position of the start of each syntax element, and would then have to use that information to build a mental model of the railroad diagram. This is extremely tedious and prone to error.

    Additionally, experimental findings suggest that blind users find it difficult to use the BNF format for two main reasons: firstly it is difficult to match up brackets ({[]}) when using a screen reader. The blind user cannot draw lines connecting matching begin and end brackets as sighted users often do to understand BNF; secondly, there is an excessive memory load for blind users for complex examples rendered in BNF.

    The syntax description shows exactly the same information as the equivalent Railroad Diagram and may be rendered automatically from a common source.

DOTTED DECIMAL NOTATION

    The dotted decimal rendering of railroad syntax diagrams does not use the horizontal positioning of syntax elements to convey meaning, and is thus accessible by blind people using a screen reader with speech synthesis. Instead it places each syntax element on a separate line. It is thus a sparse representation which requires much more paper than the origi...