One Document Category for Multiple Invoice Types
Payables predefines a document category for each invoice type. So, it seems that payables recommends document category with respect to invoice type. However the purpose of document category is to generate unique voucher number. This means we may use one category for multiple invoice type if needed.
Actually, we want to use document category to generate sequence of unique Voucher Number with respect to the physical locations of our company instead of invoice type (i.e DC_A for location A, DC_B for location B, & so on). Also note that users of all locations are working on all invoice types (i.e. std, pp, dm, etc.).