My default assumption is that if people talk about "0.8FTE", they mean 80% pay for 80% time and 80% output, whereas "4dw" _should_ equate to 100% pay for 80% ti

My default assumption is that if people talk about "0.8FTE", they mean 80% pay for 80% time and 80% output, whereas "4dw" _should_ equate to 100% pay for 80% time and 100% output. If it's anything other than 100/80/100, it's flexible work rather than a four-day working week.