Oh, I get it. So they had them listed by month at least. Of course, that makes total sense. If they take a name out, it messes up the total, so they have to have the MAE thing. Sorry, I read it so quickly I missed that sentence that made it clear.
THE index is alphabetical. The index you see is for FIVE YEARS.
1960. 1961. 1962. 1963. 1964.
When printed out, if there were two births in those five years for JOHN SMITH then the names would appear one underneath the other.