I have a spending chart.  For each transaction I list the predefined category
that the transaction falls under.  There are many categories and some of them
are repeated many times in one month.  What I would like to do is create a
box at the bottom of the sheet that will list only the categories used, not
all possible ones.  The used categories change on a monthly basis and I'd
like this spreadsheet to be a template that will work for all months.  Is
this possible to do in Excel?

Thanks in advance for the help.