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Etymology
Probably from

Pronunciation

 * Regardless of the variable orthographic representation of this suffix it is always pronounced roughly the same due to the spirantization of /b/ and reduction of non-initial short vowels.

Usage notes

 * The conditional converb is oftentimes considered disjunct, meaning that the subject of the first clause is not the same as that of the second clause, but it can be used in same-subject constructions as well. If the subjects are different, the subordinating subject takes the accusative case (example 2 above). If the subjects are the same they are often omitted.