php - Magento order status change event -

I'm writing a Magento extension to export orders. I want to export orders when the order is processed or completed Is marked as.

What is the best way to do this? Is there an event for change in the status of the order? Or is there any event to save any order?

Thank you! This event " sales_order_place_after

" Every time an order is saved " >

I do not believe there are changes in order status, however