From Add or edit enterprise custom fields in Project Server:
To add a field to the formula, click Pick field, point to a field type, and then click the name of the field that you want to reference. To reference an existing Enterprise Custom Field, point to a field type, point again to a custom field type (such as Custom Date or Custom Finish), and then click ...
Product lifecycle management (PLM) is used in Automobile, Aerospace and similar industries for new product development and major redesign
From the Wikipedia article: Product lifecycle
PLM systems help organizations in coping with the increasing
complexity and engineering challenges of developing new products for
the global competitive markets.