olemus
teostusetu operatsioon
= an operation that lacks an implementation

ülevaateid
https://en.wiktionary.org/wiki/Appendix:Glossary_of_Unified_Modeling_Language
https://wp-systeme.lip6.fr/rbendraou/wp-content/uploads/sites/10/2023/01/modelingwithuml_architecturalviewpoint.pdf