How does the 4-1 conversion ratio work?

Pse here. So I was told since one of our senior clerks was resigning, I was going to convert to a career clerk position. Now I’m hearing that it’s possible they might have to transfer someone in because we’ve had too many conversions without a transfer. I understand it’s 1 transfer per every 4 conversions.

My question, what does that mean exactly? Is it only PSE to regular conversions that count? We’ve had regulars put a bid in for other positions that have opened up in our office, does that also count as a conversion?