# Diff PreferencesHistory | Edit

To configure the SVN Diff options, open the Preferences dialog box (Options > Preferences) and go to Diff.

The following option is available:
Compare With External Application
Specifies an external application to be launched for compare operations in the following cases:
• When two history revisions are compared.
• When the working copy file is compared with a history revision.
• When a conflict is edited.
The parameters \${firstFile} and \${secondFile} specify the positions of the two compared files in the command line for the external diff application. The parameter \${ancestorFile} specifies the common ancestor (that is, the BASE revision of a file) in a three-way comparison. The working copy version of a file is compared with the repository version, with the BASE revision (the latest revision read from the repository by an Update or Synchronize operation) being the common ancestor of these two compared versions.
Important: If the path to the external compare application includes spaces (or any of the subsequent options or arguments), then each of these paths or tokens must be double-quoted for the Oxygen XML Editor to correctly parse and identify them. For example, `C:\Program Files\compareDir\app name.exe` must be written as `"C:\Program Files\compareDir\app name.exe"`.