For unknown reasons the Index page has been marked as immutable, thus I have to add link here
Notes for GnuPG users on several platforms (except maybe Windows)
General Remarks
Always use a current version of GnuPG Version >= 2. (There are only a few rare execptions to this rule.)
Debian
Note that the gnupg2 Package may look in different systems paths compared to a vanilla build and what its documentation says.
E.g: wheezy looks in /etc/gnupg2/trustlist.txt but the docs differ (Debian defect #725804).