Before creating any cost rules, we recommend that you identify the factors that drive cost rates, and the order of precedence among them. This can be done in tabular form, as in Table 2-2. Example cost rule table.
Note: Your practice table should not contain conflicting rules. This means that for any particular transaction date and set of factors, there should be only one rule effective for that date that specifies these exact values for each driving factor, except default resource rate values. PPM prevents conflicting rules.
When the system determines a cost rate, the rule table is filtered to include only the rules that match the driving cost factors. This leaves only the rules that are effective for the transaction date and exactly match the values in the driving cost factors, or the rules that apply to any value for the driving cost factors.
From this filtered set, the system determines which of these rules apply. The precedence of the cost factors is from left to right across the table columns. For each driving cost factor from left to right, the system checks whether any of the rules exactly matches the driving value. If so, then all of the more general rules that apply to any value for this driving cost factor are ignored. This process continues left to right until only one rule applies.