The Time Spread Weighted family is for the situation where you have a fixed amount to be spread over a timeperiod, but the rate at which this occurs varies, and you want to closely specify that rate. There are three ways the rate can vary:

• It can vary on a recurring annual, or seasonal basis within the year. This is what UniSpreadS does, which does a straightforward UniSpread where the rate varies throughout the user-defined seasons of the year.
  
• The total amount dispersed can be spread along a user-define profile as specified in the Weights variable of WeightSpread, where each weight is applied to an equal mini-timeperiod of length = (Finish-Start)/Number of Weights. This is effectively a user-defined curve. The weighting applies to the amount disbursed in each period and, because each mini-timeperiod is of the same length, to the rate in each mini-timeperiod.
  
• The rate of disbursement can vary in a defined, step-like manner as in FWeightSpread, dependent on predefined dates of when the stepped changes take place. Because the function is required to specify an exact Total between the first of the FromDates and the Finish date, the only thing that is not pre-determined are the stepped sequence of annual rates themselves. Instead, the relative Weights of these annual rates are specified, which enables the function to determine the exact annual rates that would exactly disburse the Total, and then apply them to the timeperiod specified by Time and Base.