To compare files using another application, define an external format.
1.Choose Tools | File Formats 
(Beyond Compare | File Formats on macOS) to open the File Formats dialog.
2.Select a format.
3.Click the General page.
4.The Mask should be the set of file types it handles.
▪The Quick compare command line will be used whenever rules-based comparison results are needed. The return code should be 0 for a match and 1 for a mismatch.
▪The Compare view command line will be used whenever a comparison view is needed.
▪The Quick merge command line will be used whenever rules-based merge results are needed. The return code should be 0 for a match and 1 for a mismatch.
▪The Merge view command line will be used whenever a merge view is needed.
▪The Description can include any text you want.
