degrees of triad isotacticity, syndiotacticity, and heterotacticity

https://doi.org/10.1351/goldbook.D01573
The fractions of @C01287-1@ in a regular vinyl @P04735@ that are of the mm, rr and mr = rm types, respectively. In cases where triad analysis is not attainable, the diad isotacticity and diad syndiotacticity may be defined as the fractions of @C01287-2@ in a regular vinyl polymer that are of the m and r types, respectively. (m = @M03838@; r = @R05026@).
Source:
Purple Book, 1st ed., p. 45 [Terms] [Book]