time characteristic formula

Hi gurus...i was wondering if it is possible to calculate periods of time between 2 time characteristics, i mean to create a formula or a calculated key figure based on that two time characteristics.

Example:

i have ztime1 and ztime2 each one with specific dates and what i want to do is to do a formula like:

ztime2-ztime1 = x days

is it possible to do it at the BEx?

Thanks