แม่แบบ:Certification Table Entry/Sales/PolishPeriod/doc

This helper template calculates periods for Polish certifications, as stated in [1] and [2]. The first source was given priority as it is more public.

It returns:

Before April 1997	Before June 2002	Before June 2004	Before July 2005	From July 2005
1	2	3	4	5

Returns 0 if the data provided is not sufficient.