This feature is available in UEStudio only.
The "Update (special)" command for Subversion can be accessed via two ways:
This command opens a dialog where you can set options prior to running the Subversion update command.
The Account field shows the name of the Subversion account as configured in UEStudio. Click the Modify button to open the CVS/Subversion - Accounts/settings dialog and add, remove, or modify accounts.
If Update using most recent revision is checked under "Revision options", UEStudio will update your local copy of the repository with the latest changes in the repository on the server. If this is unchecked, you can then use the Revision field to specify the exact revision in the repository's history that you'd like to update to.