Logic script: reading value when empty or 0

Hi,

-we are on CPMBPC release: 810 SP-level: 0004

The requirement is to read data from 'January to November' depending on where value is and write on 'December'.

So, script reads data in JAN and if there is value then writes on DEC but if value=0 or empty then move to FEB and so on..........until it finds value.

How is it possible to read when value is empty or 0?

thanks

Ahmad