The IMS Abstract Framework (IAF) is a device to enable the IMS to describe the context within which it will continue to develop its eLearning technology specifications. This framework is not an attempt to define the IMS architecture, rather it is a mechanism to define the set of services for which IMS may or may not produce a set of interoperability specifications. In the cases where IMS does not produce a specification then every effort will be made to adopt or recommend a suitable specification from another organization.
This Abstract Framework document describes the general architectural assumptions that underlie IMS specifications and other technical documents. This is a living document which is likely to evolve and be extended to include areas not covered in the current version.
Comments and Questions on the Abstract Framework should be posted in the IMS forum at http://www.imsglobal.org/developers/ims/imsforum/categories.cfm?catid=17
For an overview of the Abstract Framework, you can download the Abstract Framework Review document (pdf)
IMS Abstract Framework - Version 1 - PDF