Well, I worked on starting to update Openbravo POS database from my PDA data, originally tickets and ticketlines. I will publish the results on the Openbravo Development wiki I created, so far so good. Will update sourceforge with the latest code. This means, an end user can create tickets (openbravo pos sales orders) and when sync happens, these tickets can be scrutinized from the Ob POS itself, and exported to the Ob ERP. These relationships on these tables can be very convoluted. I have not found good specs on it. I just basically using pgAdmin III write raw sql and test it inserting/selecting/modifying dummy data. Interpreting the errors, and going back to the drawing board. No wonder I have a beta, this by no means is stable code.
I noticed also people downloading the soft but they are not registering it. I am sorry but no email, no key. If they think, they can hack the key, look be my guess.
I am also keeping my eye on the Openbravo ERP so when I finish this one, you are next, and Magento
http://www.magentocommerce.com/support/magento_core_api I will describe Magento as an unbeilabele piece of code written, I mean the best never seen such a great web app.