On WPD, we make a lot of use of MediaWiki's templates. Almost every single page in the wiki uses a large number of templates to structure its output. However, templates are complicated to understand, and often they are strongly interconnected in odd ways. This means that a single error in a template definition could have far-reaching consequences. New templates or substantive changes to templates need to be carefully considered with how they fit in with the rest of the templates, and to make sure they don't do anything crazy.
For all of these reasons, we have a group of template wizards in the Template Corps.
Guidelines for making changes to templates
The general rule of thumb is that small tweaks to existing templates need a single SGTM ("Sounds Good To Me") from one of the members of the template corps. More substantive changes (including new core templates, changes to form organization, adding additional SMW queries, and information architecture changes) require a consensus of Template Corps members to agree on the technical implementation strategy.
For small changes, often it's easiest to raise a member of the Template Corps on the IRC channel. For cases where you can't find someone or the change is bigger, send an e-mail to email@example.com with "[templates]" at the front of the subject line.
Canonical Membership List
Only Template Corps members should modify this list in accordance with the "Inducting New Members" section below.
Inducting New Members
We welcome as many members of the Template Corps as possible. In most cases we'll automatically induct members after they've demonstrated strong working knowledge of how the templates are structured and implemented fixes. If you're interested in how to gain that knowledge or want to formally ask to be included, reach out to one of the members above.