Hi YATW,
Thanks for getting in touch. We know the threads on trans people and trans issues are wide-ranging and so it can perhaps feel a bit difficult to know what is and isn't ok. It sounds like previous posters have given you a brief but pretty accurate rundown of how things are.
To be honest, it's probably much more simple than many people think. There's no line in the sand, certainly, other than the usual Talk Guidelines, which we think cover most eventualities and we moderate using them exactly as we would with any topic. So, while we are all for freedom of speech on every side of a debate and think it's important that people can share their thoughts on important topics, we will always delete reported posts that we feel are aggressive, are personal attacks or are designed to belittle, cause upset or inflame.
It is important to remember that bit about 'reported', though. We are post moderated so if a post isn't reported to us we probably won't have seen it, so do always hit the report button if you want us to take a look at something.
It's just a case of everyone being reasonable and civil really. We find the vast majority of Mumsnetters are happy to follow that guideline and so it's not really useful or necessary to have a prescriptive list of words and phrases or behaviours that are or aren't acceptable. We think, on any topic to be honest, that if people post with genuine intention and in a civil way, that's usually enough to keep things pleasant for everyone.
If you do feel that some posts are not made in this spirit or have been overlooked please do send us a report and we will always be happy to have a look at them.
Hope that answers your question.