I fond similar questions on the site, so decided it was the right place to ask it here. I have provided those questions in the comments. And the question was not just closed, it was deleted by a moderator, so I cannot ask for undeletion and cannot expect someone to even comment...
Why isn't it good for this site if there are similar questions already asked?
Similar questions:
Are there standard practices when writing a spec for a software development project?
What is the standard for modeling modern applications prior to development?