lisa - standing does mean what you say, which is similar to the definition dgu has linked to. However, I would add that standing generally means foregoing relationships with other people until you decide to stand down and "move on" to a life that does not include your marriage to your MLCer.
And as the article says, it is lonely. That is why, from time to time, people like me question "standing". If my H is like this for years, or never wants me back, at what point do I say, "ok, I am done. I would like to feel loved and appreciated again by someone and, what is more, I want to give love and appreciation to someone that knows that when I do so, it means something. I refuse to put his MLC before my needs for recipricol love anymore".
I am sure that many of us feel like that from time to time. If you are lucky your MLCer will seek to reconcile before you reach that point, but it is definitely a personal choice to decide for yourself when and what means enough is enough. I, for one, am standing for now, because I am not sure how I feel and do not want to launch myself into a relationship and then wish I hadn't and I also know that I need some healing time, some time to really look after myself and work on myself before I can really offer myself to anyone new and before I would be able to work on my R with H were to come back. I know, though, that at least for me there will be an eventual limit, when I feel that I do not want H back, or when I decide to start dating. I don't think I could wait around for 5 years or more. For some people standing is a thing of faith, whereas I am not particularly religious although I do believe strongly in the ethic of treating others as I would like to be treated. Therefore, I see standing as a sort of grace period after the relationship has been torn apart. A time to heal, to think, reflect on my own life and direction and not make any rash decisions. I think that the definition is quite loose, so it is possible to encompass various points of views...