While determining the residue in the differential equations -res for the node_dof records, the contribution for each primary unknown equation can be multiplied with a separate factor. Here factor_0 is the factor for the first principal unknown, factor_1 is the factor for the second principal unknown, etc. A factor should be specified for each principal unknown.
With these factors you can put special importance on the equation for one (or several) principal unknowns. If this record is not specified, all factors are taken to be 1.