I think it is very dangerous to use the term "holding" in a topic. The "holdings" of a case are not always clearly identified, can be numerous in number, and often important holdings do not become clear until they have been interpreted by subsequent decisions.
Josh Zive As any person who has to brief cases in their first year of law school can attest, a focus on the clear "holding" of a case (if there even is one) can be of limited value and difficult to execute. In fact, it is not unusual for decisional discussions that begin as dicta to eventually be treated as holdings later down the road by courts.
Also, I worry that the labeling of certain aspects of cases as "holdings" by Westlaw and lexis will create an arbitrary and incorrect test for topicality.
All in all, I think at least with "decision" you have a fixed and objective target. This will not be true with "holdings" or "precedents".