1. Roots (Athematic, Semithematic and Thematic) are not very productive. They can have only one Stem, or have multiple Stems opposed to each other.
2. Reduplicated stems tend to be different after the Stems; those in occlusive and in -u- are extended Roots, used mainly in verbs. Those in -s and -u are rare, and are mainly used for other Stems.
3. The most productive ones are those with -i, -e and -a, closely related. Those in -e and -a have mostly Present uses, as those in -sk- (Thematic) and in -n- (Athematic or Thematic).