An essential part of the maintenance control is the work order system that is used for planning, executing and controlling maintenance work.
The work order system consists of necessary documents and well defined flow process of the work
order.
The documents provide the means for planning and collecting the necessary information for monitoring and reporting maintenance work.
Maintenance control has received a considerable interest in the literature. Duffuaa et al. (1998), Neibel(1984) and Kelly (1984) each devoted a chapter in their books on maintenance
control.
Al-Sultan and Duffuaa (1995) advocated the use of mathematical programming to accomplish effective maintenance control.
Gits (1994) presented a detailed structure for maintenance control.