This question is too broad, and the answers will be vague at best since "significance" is very subjective. In addition, the circuits you ask about need to be defined, preferably with schematic. These names aren't standard, or at least not in common use. It could be OK to have each circuit in a separate question, with schematic or definition, and ask what practical real-world applications it might have or has been used for.

I am aware that most of the names are not very well known - and that's why I ask. I am sure that someone will only answer if he has a positive example for a professional application. Of course, I cannot and do not want to present any circuit diagrams or even explanations here. It is something like a general survey. Is that not allowed? I have replaced "significance" by "application".

I support the question and this kind of questions. I think that, in addition to specific questions, there should also be general questions. CoDidact will only benefit from this.

@LvW: So you're really asking if anyone recognizes the names or abbreviations. They may have used a circuit like that, but be unaware of what you call it. However, that's not how your question reads. It's written implying we are all supposed to know what those names mean.

@Olin Lathrop. Could be that I was not able to express myself clear enough (English is not my mother tongue!). I am only interested to learn if one (or more) of these novel active building blocks has more than a theoretical meaning only. That is all! For example: The AD844 is an integrated circuit that can be used as a CCII. Of course,I do not assume that "all are supposed to know what those names mean". The same to me: I do not know the secific properties of most devices.

@LvW: I've already told you what to do if you want to know what common applications a particular device has.

I must admit that I am disappointed. Did I express myself not clear enough? Many active blocks have been introduced in the past - I have mentioned some of them. And the only thing I am interested in is to learn if any member of this forum knows about a commercial realization/application of one of these building blocks? Or should we look at them from a purely academic point of view only? My question can be answered with only one sentence. And you are closing it because it is too "generic"?

@LvW: You are asking about many different circuits, and mixing two different concepts into the same question: Whether people recognize the names you used above to know the circuits, and whether they know of real life uses for those circuits. That's too much for one question, and makes the composite question really annoying. Either explain the circuit and ask about applications, or ask whether the name is recognized. It's not clear which you really want to know.

(Quote):"...mixing two different concepts ...: Whether people recognize the names you used above to know the circuits, and whether they know of real life uses for those circuits." I did not ask if somebody is able to recognize the names. I think, if somebody can answer my question about commercial application of one device he was able to recognize the name before. If not, he will not respond. This sounds logical to me. Too bad - but I must respect your decision.