Mostly right, but kind of simplistic and misleading, especially this statement:
If you write on your invoice ?Art Charge? or ?Digitizing Charge,? your customer owns the art and the digitizing. If, however, you write ?Art Preparation Charge? or ?Digitizing Preparation Charge,? you/your company own it, mostly because you?ve clarified the matter with appropriate written policy.
The writer fails to mention the issue of copyright as the thing that is being sold, not artwork.
"Art Charge" is NOT appropriate written policy for copyright transfer.
The customer does not own full copyright unless it is explicitly written that way. The invoice would have to say something more specific like "Transfer of copyright" or "Sale of original art."