Once the Cost Definition is set up, you can link it to a Meter, especially if you want to use the costs in Budgeting. or Browsing Data.
A Cost Definition can be used for the Unit rate within the the Budgeting. Activity. This will enable you to use your metering data for the usage, and a Cost Definition for the cost.
It can also be used in in Browsing Data to see your metering data as costs.
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The Cost Definition now shows in the Cost Definition section and will be used to define the cost per unit in the Budget.