This research presents two switching techniques using SOT and SLACK, as complementary sequencing rules, to show that they are practical procedures to control a job shop. These two approaches are:

• Static switching of the complementary rules.

• Dynamic switching of the complementary rules.

This study also presents questions which arise in creating different switching rules or procedures for an interactive scheduling system.

It is also developed a normalized objective function to measure the balance of the best properties produced by SOT (low flow time) and SLACK (low tardiness). It should be noted that even though such a system could be viewed as complex and expensive,it is not. Computational requirement will be slightly increased, but no more data is required than is expected for a typical scheduling procedure.

Finally, a procedure to calculate the upper and lower limits is presented for dynamic switching procedures.