definiens: means, in each case pro rata temporis, with respect to any [COMPANY] Activities to be performed by [COMPANY] prior to itsexercise of a Co - Development Option ( a ) during the first Contract Year, the portion of [ * * * ] [ * * * ] [ * * * ] [ * * * ] Dollars ( US $ [ * * * ] ) corresponding to such part of theCalendar Year that is covered by the first Contract Year ; and, ( b ) during each Contract Year thereafter, the result obtained by multiplying $ [ * * * ] by the sum of(1+CPI ) where CPI is a fraction, the numerator of which is the difference between the Consumer Price Index as of the last month of the immediatelypreceding Contract Year and the Consumer Price Index as of the month immediately preceding the Effective Date and the denominator of which is theConsumer Price Index as of the month immediately preceding the Effective Date