Mary - for background see http://www.openvpms.org/documentation/csh/1.7/concepts/pricing and http://www.openvpms.org/documentation/csh/1.7/concepts/products

So to answer your second question, the equivalent of your BOM is roughly the Template product. Note as a result of your question, I have expanded the description of a template in the above reference to read

So this is different to the traditional BOM approach which would just show the BOM item on the invoice but generate its price from the sum of the prices of its components.

Your question about the difference between the fixed and unit price should be answered by the Concepts|Pricing reference above.

Now to your "selling and dispensing prices" question.  The Dispensing Units and Dispensing Verb are used when generating the label - so the system can generate 'Give 4 Tablets' and 'Apply 3 Drops'. The Selling Units can be used as an item descriptor on the invoice (though we don't - our invoices just show 'x 3' for the quantity, and the standard invoice that comes with the system just has a quantity column and does not display the Selling Units).

There is also a Selling Units field for the Unit Price. Again as a result of your question, I have expanded the description of the Unit Price in http://www.openvpms.org/documentation/csh/1.7/product/tabs to read

I hope this answers your questions.  Thanks for asking them - they showed up a couple of deficiencies in the CSH text.

Regards, Tim G