olemus
(a) sektordiagrammi esitus segmentjaotusega rõngana
= representation of a pie chart as a segmented ring
https://www.edrawsoft.com/infographics/images/various-infographic-ring-charts.png

(b) mitmetasemeline sektordiagramm,
kontsentriliste segmendikihtidega,
mille keskmes olev ring kujutab kõrgeimat taset;
kasutatakse hierarhiliste andmete esituseks
= a multi-level pie chart, with concentric layers of segments, where the circle in the center represents the highest level; is used to represent hierarchical data
https://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Disk_usage_%28Boabab%29.png/220px-Disk_usage_%28Boabab%29.png