None of these sets of standards or guidelines are particularly intuitive or easy to use, but there is no better way to ensure that accessibility and usability barriers in your software are identified.
ISO 9241-171
Ergonomics of human-system interaction - Guidance on software accessibility
This is by far the most comprehensive and technical standard, drawn up by independent international standards experts, and covering all disabilities and all aspects of software. There are examples clarifying many of the statements, two priority levels ('Required' and 'Recommended'), and a handy checklist designed to help with recording testing results.
The only trouble is that because of its complexity and technical nature, and with upwards of 150 individual statements, it is difficult to interpret and apply. Luckily, not every statement is relevant in every situation. Drawing up a subset of statements based on ISO 9241-171 but tailored to the particular software environment will make the use of this standard much more achievable.
Buy the ISO 9241-171 standard
IBM software accessibility checklist
IBM has taken a very proactive attitude to accessibility for a long time, and the IBM software accessibility checklist is one of the best tools on the internet.
The main strength of this checklist is that there are not too many checkpoints - just 18 altogether. This is also a weakness, since many aspects of accessibility are not included, but the most important ones are there. There are no priorities associated with any of the checkpoints.
Another strength of this checklist is the background information that is provided. The rationale behind each of the 18 checkpoints is given, along with techniques for implementing accessibility in software being developed and built, and testing tools and techniques.
As well as the checklist itself, the IBM Human Ability and Accessibility Center contains information about software accessibility test tools and additional references on software accessibility issues, plus developer guidelines for other types of ICT interfaces such as Web and Java.
Section 508
Amended in 1998, this is the United States legislation that requires Federal agencies to make their electronic and information technology accessible to people with disabilities. The law applies to all Federal agencies when they develop, procure, maintain, or use electronic and information technology.
The conformance statements relating to Section 508 were updated during 2007, with input from experts in Canada, Australia, Japan, Europe and more. Until the revision is published, the section about software applications and operating systems contained just twelve statements. Most related to usability for people with sight impairments, and other types of disability were covered sketchily or not at all.
Despite this, Section 508 legislation has made a big difference in the US, because software developers have had to make their products more accessible, or face losing business in the largest IT market in the world. Those of us living outside the US have also benefited from more accessible products in the global software market.
Further information about Section 508 legislation.
Irish IT Accessibility Guidelines
The National Disability Authority (NDA) is an independent agency under the Department of Justice, Equality and Law Reform in Ireland. The NDA has commissioned guidelines to provide direction on making electronically delivered services accessible to people with disabilities.
The guidelines for application software have 17 statements and two levels of priority. The website also contains some helpful information about a general process by which accessible IT can be developed successfully.
Further information about the NDA IT Accessibility Guidelines.
Tiresias checklist for software applications
The Tiresias website, run by RNIB, contains lists of guidelines for the design of many types of ICT systems, including software. A checklist of around 75 statements is available, which also identifies which disability types are likely to be impacted by each statement. No priorities are given, and there are no examples or explanation of any of the statements.
Further information about the Tiresias checklist for software applications