Science Fiction, SciFi, Space Opera and Fantasy are four terms that are used to designate imaginative fiction. They are often used to designate different levels of scientific rigor in forming the background of a story. To the best of my knowledge there is no governing body or rigorous certification process to use any of these terms.
These four types of literature are those that take place in settings that are not dealt with in main steam or historical fiction. In much of imaginative fiction, from sword and sorcerer to many horror stories, no attempt is made to stay within what scientists describe as the laws of physics. Some may stay with certain other bounds such as epic fantasy or occult spiritual beliefs, but whatever they use as their milieu, it is done without regard to the scientifically accepted laws of physics.
On this site the term 'Science Fiction' is used only to mean that some attempt is made to keep the action and setting within what is allowed by the laws of physics. It is only in this most general sense that I use the term. There are some that say the only true 'Science Fiction' is that verified by scientists in the field. The inventions mentioned are verified by equations, and are usually extrapolated from the latest findings. This has also been called 'hard' science fiction.
These stories do not fit into that category. Nothing beyond high school math has been used in crafting any part of these stories. We have no one who can READ the equations used in advanced physics. The math and science is used to make the stories seem believable enough to live in, and that really means keeping up with, or slightly ahead of, what is in the popular press. To some that makes these stores are either SciFi or Space Opera. I do not have a problem with either of those labels. I believe one is being true to the spirit of Science Fiction if one bends the story to fit the facts known at the time instead of bending the facts to fit the story.
All science fiction has a shelf life in this regard. In general the harder the science, the shorter the shelf life. That is not always true, what was once near future has become mainstream in some cases. Today even mainstream fiction quickly becomes a period piece. A detective story written before cell phones is already something from a different age and seems less 'real' than Stand On Zanzibar.
An example of shelf life is the existence of Cynd. When many of these were first written, the existence of a mega-planet/brown dwarf in the 61 Cygni system was just about an accepted fact and it's parameters were estimated and published. It was written into many of the stories during the 70's and 80's. Later measurements have indicated that it is probably not there, the latest I have seen preclude any body larger than 2.2 Jupiter masses. I have not gone back and taken it out of the stories. In the near future the bodies at all the nearby stars will be mapped and all stories trying to stay within the bounds of reality will have to use what's there. All of us who invented scenery out there will be rendered obsolete.
Kassidor makes use of a lot of 'genetic' or biological science, most of it unexplained. These are not reference books on how to achieve the wonders of Kassidorian biological science, but only some speculation on what it might be like if we do. Our own biological science is in such infancy that speculation on the details of how the services would be produced and delivered is pointless. In the stories they are delivered in ways that are convenient for the consumer and fit within the culture.
Some undergraduate level Anthropology, Archeology, History, Political Science, Psychology and Sociology, as well as further background readings in these subjects has been used in constructing the society of Kassidor. Again, most of the further readings are not far beyond the popular press level. The opinions expressed here are, of course, entirely my own. There can be no studies as of yet on the social effects of eternal youth. It is my sincere hope that someday those studies will be carried out, whether or not it leads to a society like that of Kassidor.
The only area where these stories use more advanced knowledge than a high school grad who follows science in the popular press is regarding O.S. internals and digital logic. That knowledge serves as the foundation for the 'Angels' and other simulates that appear in many of the stories. Thus it may become obsolete the soonest. What already seems obsolete today is that the Angels retain human-like personifications in simulation.
However, the purpose of the stories was not to show how fast technology will race off away from us, but to retain characters that would still have enough human traits that the non-human traits will be visible. I hope they retain enough human traits to be entertaining, and to bear some relationship to the issues of our times. The setting is only as different from Earth as it has to be, any closer would be extremely unrealistic. The technology is about the minimum required for people from Earth and Kassidor to meet and is seldom the focal point of the plot.