Modifications fct

— The lines in range f of the first revision were replaced with the lines in range t of the second revision.

For example, in the change command 8c8,9 tells us that line 8 of revision 1.11 was replaced by lines 8 and 9 in revision 1.12.

Additions lar

—The lines in range r of the second revision were inserted after line l of the first revision.

For example, the change command 9a11 means that line 11 was inserted in revision 1.12 after line 9 of revision 1.11.

Deletions rdl

— The lines in range r from the first revision were deleted; line l is the position where they would have appeared.

For example,  the change command 17d18 means that line 17 was deleted from revision 1.11.