A link that launches an application isn't recognized as a link in JIRA (despite being proper Markdown). For example, the following link is designed to launch TortoiseSVN with the given repo url.

[Revision 4635](tsvncmd:command:log?path:http://10.1.1.13/svn/SampleDirectory/trunk?rev:4635)

but it results in the following:

[Revision 4635](tsvncmd:command:log?path:http://10.1.1.13/svn/SampleDirectory/trunk?rev:4635)

This code does format correctly on Markdown editor sites such as http://dillinger.io/

If this functionality were to exist, I could create links that launch TortoiseSVN within my Issues.