HI,
The system will check for calendars in Following ways:
1. Company code
2. Currency
3. BP
4. Manually added in transaction (in Extras > Calendar there will be option for 2)
For a given transaction you can assign 3 different calendars based on the above inputs. The default calendars used will be Company code and Currency , in case the Company code and Currency of transaction is same. In case the transaction currency is different the calendar used will always be in reference the currency. Same is the case for Reference interest Rates. all the Interest flows will by default use the calendar associated with the Ref. Int. Rate.
Apart from this the system also check BP and you can manually enter it in Extras > calendars. This will be applicable for the structure flows, for interest flows if you want different calendars you have to manually add in conditions or by default it will be always the transaction currency calendar.
In case you have a need to use more than 3 calendars. you would have to define a composite calendar with the associated countries and add manually in the transaction.
Regards,
Nikhil