Mathcad version 15 has in-fix and post-fix operators; Prime never has, although there are numerous requests in the forum.
That is, I thought Prime didn't have a post-fix operator UNTIL I looked carefully at the units for temperature (°C and °F.) Both of these are functions (masquerading as units) that convert the absolute temperature that Mathcad carries to the more commonly recognized temperature scales. These are not simply ratios (like we would have to convert feet to millimeters) they require the addition or subtraction of numbers in addition to the ratio.
Since Prime already knows about post-fix (demonstrated by temperature conversion) why can't this feature be provided to users as an operator?
There have also been discussions about a dB function; but it should be possible to create a dB unit function along the thoughts of temperature.