The authoring system XAIDA [10], which stands for eXperimental
Advanced Instructional Design Advisor, was developed
for creating tutors to teach maintenance of physical devices.
The Expert Module of XAIDA consists of four shells for
teaching the physical characteristics of the device, the theory
of operation of the device, the procedural operations of the
device, and troubleshooting problems with the device. A fixed
set of instructional strategies is associated with each shell.
CREAM Tools [11] is another authoring system which allows