I read this at least 20 years ago, maybe more. It may be a short novel, in a book by itself, or a rather long novella in a collection, I can't remember. It was a pretty intricate story, involving various themes that interacted with each other. But I can't put them in any chronological order in the story, so I'll just put them down as I remember them
- travel to the Moon was commonplace
- one character used a ship called Heinlein, or Robert Heinlein, or Robert A. Heinlein
- there was still no air on the Moon, but pressure suits were getting extremely light and almost invisible
- maybe as pressure suit, or maybe only when there is air, some people wore clothes that made them partly invisible. It sounded like "nullflesh" or "nullskin", or "null something"
- sex change operations were commonplace, some people would change many times in their lifetime
- even more common were body-modification operations without sex changes
- I remember one line, about a character who was male at the beginning and always had only rather modest body-modifications, but had become female (or had decided to do so soon) and told some friend on the phone that the new body was (or will be) very different from the previous one because, once female, the phrase "whore of a different color" will apply ("whore" was not a misprint, but a deliberate pun on "horse").