Merging Differences
After running a file or directory comparison in a comparison window, you can merge differences that exist between the directories/files in the two panes.
In File Comparison windows,a difference (that is, a text fragment for which there is no, or no identical, corresponding text fragment in the compared file) can be copied over from one file to the corresponding location in the other file.
In Directory Comparison windows, the selected non-equal file (a file for which no, or no equal, corresponding file exists in the compared directory) can be copied from one directory to the other directory.
You use the following commands to merge a difference:
Copy from Left to Right (Alt+Right)
•For the selected difference in a file comparison, copies text from the document in the left pane to the document in the right pane.
•For the selected non-equal file in a directory comparison, copies the file from the (directory in the) left pane to the (directory in the) right pane.
Copy from Right to Left (Alt+Left)
•For the selected difference in a file comparison, copies text from the document in the right pane to the document in the left pane.
•For the selected non-equal file in a directory comparison, copies the file from the (directory in the) right pane to the (directory in the) left pane.
In file comparisons, the source difference is copied in its entirety (i.e., the entire unit highlighted in the current difference background color overwrites the entire difference in the target document). Merged differences in file comparisons can be shown in a different background color. This setting is made in the File Comparison tab of the DiffDog Options dialog box.
To merge a difference:
1.Place the cursor in the required difference (which could be anywhere in the document) or navigate to it using the Next Difference 
or Previous Difference 
navigation commands listed above.
2.Select the menu option Diff and Merge | Make Current Difference or press Alt+Enter or select the corresponding toolbar icon 
from the Diff and Merge toolbar.
3.Do one of the following:
•Select the menu option Diff and Merge | Copy from Left to Right or click the corresponding toolbar icon or press Alt+Right if you want to copy from the left pane to the right pane.
•Select the menu option Diff and Merge | Copy from Right to Left or click the corresponding toolbar icon or press Alt+Left to copy from the right pane to the left pane.