NPN transistor CE or EC?
A bipolar transistor is basically symmetrical from C to E. In practice, it is optimized for good properties (most important: a high current amplification factor), which requires asymmetry. So a real transistor will have good properties when used as intended, but will still function as a very mediocre transistor when used with its C and E exchanged. In particular it will have a very low Beta (= current amplification factor) when used in this way, think of 10 instead of 200.