One of the ways to get around the problem of things that are simply "known" is to write them down. That's not the only trick, though. There are lots of places to write things down:
- Email: This one really doesn't work very well. It requires either the sender or the recipient to still be there later and remember that the information is available.
- Document: This is better than email, but make sure you store it somewhere centrally. Keeping it on your laptop has the same problem as email - others can't get to it.
- Document on a Central Server: This is accessible, but not the most easily searchable.
- Document in a CMS or Wiki: This is generally the easiest to update and to search. However, formatting isn't the best.
In the end, as long as it's accessible to the entire team, pretty much any method works. Just make sure it's consistent.