Guideline 1:
Support accessible authoring practices.

If the tool automatically generates markup, many authors will be unaware of the accessibility status of the final content unless they expend extra effort to review it and make appropriate corrections by hand. Since many authors are unfamiliar with accessibility, authoring tools are responsible for automatically generating accessible markup, and where appropriate, for guiding the author in producing accessible content.

Many applications feature the ability to convert documents from other formats (e.g., Rich Text Format) into a markup format specifically intended for the Web such as HTML. Markup changes may also be made to facilitate efficient editing and manipulation. It is essential that these processes do not introduce inaccessible markup or remove accessibility content, particularly when a tool hides the markup changes from the author's view.