The SLEW/EDGE module combines the function of a slew limiter for CVs and a CV change detector in one module. Slew is a method of slowing the rate of change of a CV signal, i.e. the changes are less abrupt thus being useful for things like portamento. The slew operation can be activated individually for rising and/or falling CVs.
The other function is edge detection, which can generate various gate / trigger output signals depending on the rise and fall of the input CV; this information is available on different outputs.
These merchants probably sell this module. Huh?
Tangible Waves SLEW/EDGE