Interest Rate Volatility - An entry is needed here (or enter a Term Structure on optional F7 popup input) to turn on the OAS pricing feature. Enter as a percent. To see what the numbers look like with 0% volatility then enter .0000001 in this field. See next. Pop-up Input Alternative - Enter volatilty numbers in percent that will be in effect for that year. Only enter at the points of change. Program will carry input through blank rows. Options ------- Probability that Interest Rates will Increase - Usually 0.5. But market participants usually expect that rates have a propensity to move in one direction over the other. Use next field to turn off after a few years or use F8 to control changing probabilities by year. Years Before Dropping Back to 0.5/0.5 - Time frame before turning previous field back to default probability. Pop-up Input Alternative - Enter probability numbers that will be in effect for that year. Numbers must be less that 1. Only enter at the points of change. Program will carry input through blank rows. Last number entered should be .5 to return probability back to neutral. Effective Duration Deltas - When measuring a bond's effective duration BondCalc shifts the benchmark yield curve by a nominal amount. Using new forward spot rates, and holding volatility and the bond's OAS constant, a new bond price is solved for. Using this, the OAS Duration and other measures of a bond's price sensitivity to changes in interest rates can be calculated. Also Calculate when No Calls Present - By default BondCalc does not expend the overhead to calculate OAS when there are no calls present, except when backsolving with OAS. Entering a 1 here will allow testing to see that there is no option value when there are no calls. This flag will also turn on OAS for bonds with greater than 30 years to maturity, as they take a long time to calculate. Opt Key Years for Partial Durations - If these are blank the partial durations will be broken into the benchmark years on the used yield curve. These override. A 0.5 year one will always be included.