Hi Venkat,
Fiscal Year/Period (0FISCPER) is mapped to the Posting Date, and therefore the first InfoObject mapped in this sequence is 0FISCPER from the posting date and it will get the right period/year combination from the posting date. The note in the help page sounds correct because if the 0FISCPER is mapped to Posting Date, the other two InfoObjects should get the correct values of year and period. The date that drives all this mapping is the posting date and this should capture the period in the right year.
Thanks,
MJ