If I want to auto-enter a value into a field based on a relationship, is it better to use a look-up or calculated value? What conditions would drive the use of one over the other? Assuming that I'm just copying a single value.

Well with calculated value you can use conditions to determine what gets looked by using the Lookup ( sourceField {; failExpression} ) function.

Perhaps one field requests some rate field that you need to grab a value from a Vendor Rate table, but when the field has a different value you can make the condition to use the Customer Rate table to insert the value.

Where as the lookup option is tied usually to the key fields to trigger a lookup and you only have one option as to the source of the data you desire. With a calculation it's easier to trigger a recalculation of the field, as any field that is referenced will initiate the evaluation.

With calculation entry you could even go a step further and use variables that were previously defined in a script and you only need to create records to have the values auto enter in the fields thus avoiding having to use the SetField script step over and over. Thus giving you a layer of abstraction, and can change conditionally based on business logic in the script.

Hope that helps

stephen