Many businesses assign Dimensions to Items, for instance a Product Type Dimension that they then use to analyse profitability, sales etc.

Item Charges can be used in a variety of ways IE to assign additional costs (such as import duty, shipping etc) or to apply a rebate/sales allowance/partial credit to Items. When using Item Charges you are directly assigning additional cost/discount to a selection of Items.

You only have the ability to assign a Dimension Value to the Item Charge line on the document, there is no way of assigning Dimensions based on the original source Document Lines for the movement of the Items. In an ideal world the Item Charge Assignment lines would allow Dimensions to be assigned with an option to inherit from the Source Documents (Receipts/Shipments).

A couple of Examples:

I have a Product Dimension assigned to my Items, I ship 5 different products to a customer on one shipment and 3 other products on another shipment to the customer. They then bill me for a rebate on the Items. I raise a Sales Credit Memo and add one line for the rebate and then assign it across the 8 lines of shipping, all of which could have different Product Dimensions. I can only assign 1 Dimension value on the Sales Line, not the 8 different ones. This means when I come to analyse the profitability by Product Dimension I get an incorrect view.

Alternatively, I might receive a variety of Items into stock and then get a Purchase Invoice for Shipping Charges or Import Duty that I need to apply across all those Items, these charges form part of the landed cost of the Items and help give me an accurate profit level. There is no way of assigning the dimensions correctly without posting multiple Item Charge lines. With Shipping Charges there will only be a single line and no way of knowing how that should be allocated across the different dimensions.