The SRK model was further developed by Reason (1990), who identified
action slips and failures of prospective memory as varieties of
skill-based error. Reason noted that such “absent-minded” errors are
characterized by a failure to execute an action plan as intended. Reason
placed rule-based and knowledge-based errors in the general category of
“mistakes,” as in each case these errors reflect failures during the formulation
of intentions. Reason also considered procedure violations to be a
separate and distinct class of error. Procedure violations can be defined
as cases in which the person knowingly performs a task in contravention
of a documented procedure or accepted good practice. The SRK model,
as expanded by Reason, is now one of the most widely used error frameworks
in the study of industrial and transport accidents