+added
-removed
 unchanged
@@ -186,6 +186,12 @@
--- (oldversion)
+++ (newversion)
Index: path/to/file
@@ -R,r +R,r @@ syntax. 

Those are two ranges, the one with the - is the range for the chunk in the original file, and the one with the + the range in the new file. The R designates the line number where the diff operation is started. 

The numbers after the comma are the number of affected lines in each file. 
•Every time you remove a line, the +r number will be smaller than -r. 
•Every time you add a line, the +r number will be bigger than -r
•Changing a line will add 0 to the +r number. (same scope of lines)