Now the number itself is increased as often as neccessary to create a
unique one by comparing the generated numbers with the existing ones
retrieved in the first step. In this step gaps in the assigned numbers
-are filled for some tables (e.g. invoices) but not for others
-(e.g. sales orders).
+are filled for all currently supported tables.
After creating the unique record number this function can update
C<$self> and the C<defaults> table if requested. This is controlled