General accessibility considerations

The following is a selection of the main checkpoints from the W3C WCAG 1.0 guidelines that are applicable to all included HTML content. The numbers in parentheses refer to the WCAG 1.0 guideline number. Items required to achieve the W3C AA accessibility are marked as mandatory.

Provide a text equivalent for every non-text element. Mostly this entails adding an alternate text for all images - this is a mandatory requirement (1.1)
Ensure that all information conveyed with colour is also available without colour. This is a mandatory requirement (2.1)
Ensure that foreground and background colour combinations provide sufficient contrast when viewed by someone having colour deficits or when viewed on a black and white screen. This is a mandatory requirement. (2.2)
When an appropriate markup language exists, use markup rather than images to convey information. This could be alternatively phrased: do not use images that just contain text. This is a mandatory requirement. (3.1)
Ensure that all HTML conforms to the HTML 4.01 standard. This is a mandatory requirement. (3.2)
Normally always use style sheets to control layout and presentation, but also have the ability to display without style sheets if they are not supported by the client browser. This is a mandatory requirement. (3.3 and 6.1)
Use relative rather than absolute units in markup language attribute values and style sheet property values. Use 'em' or '%'. This is a mandatory requirement. (3.4)
If JavaScript is used, ensure that the page still functions with JavaScript disabled - see accessing Ebase presentation attributes. This is a mandatory requirement. (6.3)
If there are any clickable links or buttons, ensure these can be activated with the keyboard alone - i.e. not using the mouse. This is a mandatory requirement. (9.2)
Clearly identify the target of each link. This is a mandatory requirement. (13.1)
Use the clearest and simplest language appropriate for a site's content. This is a mandatory requirement. (14.1)
Supplement text with graphic or auditory presentations where they will facilitate comprehension of the page (14.2)
Create a style of presentation that is consistent across pages (14.3)

See the W3C WCAG 1.0 guidelines for a more complete list.

Accessing Ebase presentation attributes

Ebase maintains information about the presentation attributes that are currently being used to generate HTML. These attributes are made available to a JSP via the Ebase external form interface. (See Ebase External Interface for instructions on using this interface from a JSP and detailed javadoc).

This interface has the following methods that can be used to determine accessibility information:

isDisplayInColour()
isJavascriptEnabled()
getZoomAmount()
isUseStylesheets()
calculateFontSize(String sizeString,int zoomAmount)

It is mandatory to provide the end user with the option of viewing each page without colour, and the isDisplayInColour() method can be used to check this. Note that this method can only be used if Ebase is aware of choices made by the end user - either the optional 'Display in Colour' button is displayed (See Web Accessibility Options and Attributes) or, if this information is determined by some other method, system variable $PRESENTATION_USE_COLOUR has been set to reflect the end user selection.

It is mandatory that a page should function regardless of whether or not the client browser provides support for JavaScript. The isJavascriptEnabled() method indicates whether Ebase is currently using JavaScript.

Style sheets should normally be used to mark up any content. The isUseStylesheets() method should be used to determine if the client browser provides support for style sheets. If not, non style sheets equivalent mark up should be used e.g. <font> tags.