CC onset clusters consist of:
(a) obstruent + liquid;
(b) obstruent + glide;
(c) s + voiceless stop;
(d) s + sonorant.
CCC onset clusters consist only of s + voiceless stop + r.
CC clusters are attested both word-initially and word-medially. It is not clear whether CCC clusters appear word-internally. For instance, it is possible that the word astranti is syllabified as.tran.ti - no judgments are available on this.
Source: Kouwenberg 1994: 564
Source: Kouwenberg 1994: 294
Source: Kouwenberg 1994: 553-677