separate the duration field into two fields, duration and duration units. End date calculation would then be
duration units = "months"; Date(Month(Start Date) + duration; Day(Start Date); Year(Start Date));
duration units = "years"; Date(Month(Start Date); Day(Start Date); Year(Start Date) + duration)
// etc if more duration units are anticipated
Separate the duration field into two fields: duration [number type, representing the number of days], and durationText [calculated text based on duration to figure months and years]. Then endDate is simply startDate + duration (calculation result is type Date).
Thanks for the help. I ended up creating a new table to store both the options and the number of days to make the calculation easier, and then just creating a value list with the items and using those values in second column to do the calculation.