Auto Generate Text based on existing file names

[JABarrett]

I have a form which i wish to allocate an automatic reqest number to based on
the format MM-###, i have so far managed to get the code in the form to
create the two digit month field but i wish to be able to have the form look
at the files in the folder structure and determine what the next number in
sequence is. There are two main option folders the files will be split in to
before being sub grouped by year then month. There is a drop list field on
the form with the two folder names in so the best option if possible would be
to have the number automatically generated once the option is selected from
the list as this will determine which folder it is checking the value of. I
also want to be able to save the form by the incrimental numbers, here is a
sample folder layout that will be used:

Root
-ABC1
--(year - eg. 2004)
---01
---02
---03
---04
---05
---06
---07
---08
---09
---10
---11
---12
-ABC1
--(year - eg. 2004)
---01
---02
---03
---04
---05
---06
---07
---08
---09
---10
---11
---12