I don’t think that’s any more standardized for Kosmo than for Eurorack, but @antoine.pasde2 has collected some information here:
but I think the first question should be “which CV” – anything with a summing node and either an existing on-board offset (e.g. coarse tune, octave selector, etc) or one external CV plugged in can handle an additional negative CV just fine. Other circuits might be less willing to deal with negative CVs.