Proposed shortcut: {{Shortcut|GW:Comments}}
What is a comment?
A comment is an edit placed where such edits would customarily be signed. Typical places for comments would be any talkpages (but not their headers if they have them), and some article pages used for discussion or inviting signatures or signed comments (e.g. polls or requests for adminship). An edit is considered a comment even if it is not signed, though in that case an indication of who made it may be added by others. (See GuildWiki:Sign your comments.)
Comments are personal statements, and one of the quickest ways to anger other editors is to mess with their comments. In the interest of fair debate on the wiki, comments of other users should remain intact and in context whenever possible.
If you have an issue with a comment of another editor, it is often best to explain that issue to the editor (usually on their talkpage) and allow them to correct themselves.
When can I modify my own comment?
If no-one has replied to your comment, you can edit it as you please. If your comment has been replied to, it is ok to correct spelling and other errors, and to strike passages with <s> tags like this: passage. You may make other edits to it, but should append a signed note to it indicating the change.
When can I edit the comments of others?
Comments may be modified or deleted in case of obscenity, libel, spam, or vandalism. (Invalid wiki markup is considered a form of unintentional vandalism, as it defaces the comment.) In the case of modification, you should append a signed note to it indicating the change. In the case of outright deletion, it may be prudent to notify the original editor via their talkpage.
Comments of others may be moved, e.g. to an archive; there should be a link from the original page to the new location. Commments fall under the wiki license, and thus may be copied across the wiki if proper attribution is preserved.
If a page is deleted, its corresponding talkpage may also be deleted.
On the talk pages of active users, it is up to those users to decide how to treat spam or vandalism. Comments should not be moved off a user's talkpage without their consent.
What about section headers?
Section headers serve the dual role of being the first line of a comment, but also functioning as an aid to navigate the page. If a header of a comment is unsuited to fulfill its navigation role, it may be replaced with something more suitable. In that case, the change should be clearly indicated immediately below the new header; the original header should be prepended to the body of of the original comment, so that both new and old header text are properly attributed to their respective authors.
Insert Example
Insert link to section header change notice template
On talk pages of active users, those users are the arbiters in this respect.
Administration
Users who maliciously edit comments of others to falsify or stifle debate will be warned and/or blocked. If there seems to be no malicious intent, the editor will be warned, and their action reverted.