Currently, only # format is used for issue autolinks - which is cool, but having additional formats for issue autolinks could be quite useful in some integration use cases.

New formats should go in same row with formats described in RedmineTextFormattingMarkdown and RedmineTextFormattingTextile for documents, versions, etc. So it should be something like issue#1234 or issue:1234.

Use case:

GitHub repository mirrored to Redmine SCM. Issue tracking done both in Redmine (for end-users) and GitHub (for developers). Need to properly reference GitHub and Redmine issues in commit messages and utilize Redmine's time tracking by commit messages feature.

Problem:

(remove underscores in commit messages)

The issue numbers in commit messages like "Fix #_102 refs #_13 @30m" will be recognized by both Redmine (issues 102 and 13) and GitHub (issues 102 and 13).

GitHub have additional format for issue autolinks, but still the issue numbers in commit messages like "Fix GH-102 refs #_13 @30m" will be recognized by both Redmine (issue 13) and GitHub (issues 102 and 13).

If Redmine would have additional formats for issue autolinks, then commits like "Fix GH-102 refs issue#13 @30m" will be recognized properly by both Redmine (issue 13) and GitHub (issue 102), so described use case will get a chance to live.