Default prominence patterns divide into two types: fixed and proportional. In fixed patterns, the number of prominences is constant regardless of the length of the form. Fixed patterns can be single (one prominence per form) or dual (two prominences per form). In proportional patterns, the number of prominences increases as the length of the form increases. Proportional prominence patterns can be either binary (prominence on every second syllable) or ternary (prominence on every third syllable). Phenomenal prominence systems may be either fixed or proportional. Metrical prominence patterns are always proportional. Metrical patterns are typically binary, very rarely ternary. All single and dual phenomenal patterns indicate binary metrical patterns. The simplest binary metrical patterns are the four patterns that exhibit perfect alternation. While each of the four perfect alternation patterns is attested, only a few of the possible departures from perfect alternation are attested. The pattern of attestation exhibits asymmetries that become clear when considering iambic-trochaic mirror image pairs. At most one member of such pairs is attested. With only four reasonably clear examples, ternary stress patterns are extremely rare, and is it impossible to make any significant generalizations about them with any degree of confidence.