Whatever numbering structure you use, it is always a good idea to use a
"literal" numbering system (e.g. use 001, 002, 003 instead of 1, 2, 3) so
that if/when you sort by that number, the sequence is correct.  This
applies to numeric and alpha-numeric systems, e.g. MH1996.001.

Try to anticipate the number of numeric placeholders (greatest number of
entries in that section) that you will require and set up your numbering
accordingly.

Most institutions have unique, pre-existing numbering systems, but most
can be modified to include the appropriate numeric placeholders.

Hope that helps.

Mary E.