olemus
näitaja struktuuri ja käitumise määratlus
= the structural and behavioural definition of a measure

näiteid
https://mmshub.cms.gov/about-quality/new-to-measures/types

https://cloud.google.com/looker/docs/reference/param-measure-types

https://nvlpubs.nist.gov/nistpubs/legacy/sp/nistspecialpublication800-55r1.pdf (subsection 3.3)