a for add

Let us consider an example:

65a78,81

This means ``at line 65 of the most recent checked in version, new lines are added as line 78 to line 81 in the working file''.

This is followed by the lines actually added, such as:

>   i = i + 1;
>   if (i > MAX)
>   {
>     i = i - MAX;
>   }

Note that there are four lines from 78 to 81.