Section 101. Preliminary expense budget

The preliminary expense budget
  shall contain proposed expenditures and a forecast of revenues  for  the
  ensuing  fiscal  year,  including,  for  each  tax  revenue source which
  represents five percent or more of the total forecast of tax revenues, a
  detailed statement of the methodology and assumptions used to  determine
  the  forecast  of  revenues estimated to be received from such source in
  sufficient detail to facilitate official and public understanding of the
  manner in which such forecasts are made, shall indicate  proposed  units
  of  appropriations  for  personal  service  and  for other than personal
  service, shall include a financial  plan  for  the  city  for  the  four
  ensuing fiscal years (of which the first year is the year for which such
  preliminary  expense  budget is being prepared), consistent with section
  two hundred fifty-eight, with the amounts estimated to be available  for
  discretionary  increases, as defined in section one hundred two, in such
  years, shall include the departmental estimates of  agency  expenditures
  for  the  ensuing  fiscal  year pursuant to section one hundred together
  with  proposed  sources  of  revenue  for  each  unit  of  appropriation
  specified therein and shall present a plan to ensure balance between the
  expense and revenue budgets during the ensuing fiscal year.