Digital learning resources are produced with the aid of general purpose authoring tools and (possibly) tools that are designed specifically for producing learning content . Learning Content Management Systems and Course Management Systems also provide environments for producing digital learning resources by assembling existing assets and objects.
Common general purpose authoring tools include Microsoft Word & PowerPoint; Macromedia Dreamweaver, Flash, Authorware, Fireworks and Director; Adobe Photoshop, Illustrator and PageMaker. Tools designed specifically for authoring learning content include DazzlerMax, Elicitus, IBT Web Authoring, Lectora Publisher, ReadyGo, and many others. There are also products such as HotPotatoes and QuestionMark Perception that can be used for authoring quizzes and products such as RoboDemo and Viewlet Builder that are specifically designed for authoring "software simulations." See (Nantel 2004) for a review of learning content authoring tools.
See (Chapman, 2003) for information and a review of learning content management systems.
The most important interoperability requirement for an authoring tool or environment is that it be able to ingest and publish content in standardized formats. It does not matter what format is used to store content internally.