I'm hoping I understand your question right but I'll try:
would it be possible for you to use a dictionary for this? (associative array, same thing)
and say something like:
var monthlyDP:Dictionary = new Dictionary();
monthlyDP["1st"] = "first";
monthlyDP["2nd"] = "second";
monthlyDP["3rd"] = "third";
...and so on.
that way you get direct access. Of course there are multiple ways of doing this.
Hope that starts you in the right direction.