All compound verbs combine two parts with their own meaning to create a combination word as verb. A separable compound verb is apart in the present, together in the future, and with modal verbs (kan, wil, mag, moet), and also together in the past, but with a twist - the GE is not used as a prefix, but is inserted between the two parts of the verb.
Example: Die bokser slaan die opponent uit. Die bokser sal (or kan, wil, etc.) die opponent uitslaan. Die bokser het die opponent uitgeslaan.