My friends,
Currently we have a another alternative, not be necessary to create the CDIE.
The note 145434 can increase the AT30 XFORMEL table field to 132 characters. Therefore we can assemble the following formula with two variables:
100 * ((1 + V1/100) * (1 + V2/100) ^ (360/252) -1)
where:
V1 = Constant = SPRED
V2 = Variable = CDI
Hope this helps