How does something become a Davar Shebakedusha? What is the criteria?
This question was inspired by the discussion over here. People half-standing for אלקינו in zimun
Perhaps someone can answer directly. Otherwise, this might help: Gather a list of things that are and a list of things that are not d'varim shebikdusha and see whether a rule can be figured out from the examples. I'm marking this answer "community wiki" so additions to it will be easier.
A davar shebekdusha (lit. thing done in holiness) is any ritual that requires a minyan to be done. It is called this because the Talmud (Megillah 23b) derives the requirement of a quorum of 10 for a 'minyan' from the verse (Leveticus 22:32) "Venikdashtim betoch benei yisrael" "And I will be sanctified in the midst of the Children of Israel". Venikdashti comes from the root of kedusha - holiness.
The mishna there gives these examples of things that require a minyan: