olemus
(a) = protokollistik

(b) protokollide kihtsüsteem
= a layered system of protocols

(c) protokollistiku teostus tarkvaras
= implementation of a protocol suite in software

ülevaateid
https://www.techopedia.com/definition/9005/protocol-stack

https://en.wikipedia.org/wiki/Internet_protocol_suite

https://en.wikipedia.org/wiki/Protocol_stack

https://en.wikibooks.org/wiki/A-level_Computing/AQA/Computer_Components,_The_Stored_Program_Concept_and_the_Internet/Structure_of_the_Internet/TCP_IP_protocol_stack