CVS has a default template that is used for commit messages. FreeBSD has extended it with several lines of data to allow more precise information to be included in the commit message such as the PR number, by whom it was approved and so on.

Hg runs a command called hgeditor when committing, it is a shell script that be tailored to our needs including template support.

git-commit is just a shell script which could be extended to start the editor with a simple default template