In order that the books of account during the operating period may present an accurate fiscal picture, it is essential that all obligations of a local agency applicable to a reporting period and due or accrued shall be recorded on the books of account at the end of the period. It is also essential that disbursements covering expenses which will become a charge to operations at a later date be recorded as a deferred charge. With respect to these items the procedures outlined herein shall be followed during the operating period. Similar procedures are applicable during the development period mainly with respect to deferred charges, unpaid bills and invoices being recorded during the development period as obligations only as they are vouchered for payment.