In several datasheets for electronic components, I have seen a ∝ symbol used as a prefix for a time unit, usually seconds, writing as ∝s. As far as I know ∝ is not a valid SI prefix, so what does it mean? What unit is ∝s?
Comparing different datasheets, I assume it should be rather equivalent to micro prefix, but I'm really not sure.
You can see this use for example in the BT136 datasheet describing "Gate controlled turn-on time" and defining unit as ∝s.