By default, the function minimized is the sum of squares of the errors. POWER=n.n modifies the power to which the errors are raised. POWER=2.0 is the default. In practice, POWER=2.0 is best, but smaller values, down to POWER=1.4 can be used. Below 1.4, the optimization becomes inefficient.
For publication purposes, there should be a really good reason for modifying the power used.