olemus
atribuut, millele peab olema määratud väärtus enne objekti isendi loomist
= attribute to which a value must be assigned before the object instance is created

ülevaateid
https://dev.to/imasharc/attributes-in-object-oriented-programming-languages-and-their-uml-representation-on-the-java-example-1o59

https://www.novell.com/documentation/developer/ndslib/schm_enu/data/h2vnta8j.html

näiteid
https://www.etsi.org/deliver/etsi_ts/102700_102799/10277803/01.02.01_60/ts_10277803v010201p.pdf
(subsection 4.4)