The invoice is a well known document. Its a classic master detail object.
In the head is the document number, the date and the recipients address.
In the positions are the different items with prices. The document foot displays the sum, which has to be paid.
This my datadefinition 3. this is the request to display it:
The foot displays the sum of the positions and the sum is calculated after each position changement.
The data access is ruled by a simple right based access control system.
All users are allowed to read the data. The logged in user can create records. The creator is allowed to change or delete his records.
All right are granted to the admin.