Jeff -
From the Excel help item titled "About cell and range references"
The 3-D reference style
If you want to analyze data in the same cell or range of cells on multiple
worksheets within the workbook, use a 3-D reference. A 3-D reference
includes the cell or range reference, preceded by a range of worksheet
names. Excel uses any worksheets stored between the starting and ending
names of the reference. For example, =SUM(Sheet2:Sheet13!B5) adds all the
values contained in cell B5 on all the worksheets between and including
Sheet 2 and Sheet 13.
a.. You can use 3-D references to refer to cells on other sheets, to
define names, and to create formulas by using the following functions: SUM,
AVERAGE, AVERAGEA, COUNT, COUNTA, MAX, MAXA, MIN, MINA, PRODUCT, STDEV,
STDEVA, STDEVP, STDEVPA, VAR, VARA, VARP, and VARPA.
b.. 3-D references cannot be used in array formulas.
c.. 3-D references cannot be used with the intersection operator (a single
space) or in formulas that use implicit intersection.
How 3-D references change when you move, copy, insert, or delete worksheets
The following examples explain what happens when you move, copy, insert, or
delete worksheets that are included in a 3-D reference. The examples use the
formula =SUM(Sheet2:Sheet6!A2:A5) to add cells A2 through A5 on worksheets 2
through 6.
Insert or copy If you insert or copy sheets between Sheet2 and Sheet6 (the
endpoints in this example), Microsoft Excel includes all values in cells A2
through A5 from the added sheets in the calculations.
Delete If you delete sheets between Sheet2 and Sheet6, Excel removes their
values from the calculation.
Move If you move sheets from between Sheet2 and Sheet6 to a location
outside the referenced sheet range, Excel removes their values from the
calculation.
Move an endpoint If you move Sheet2 or Sheet6 to another location in the
same workbook, Excel adjusts the calculation to accommodate the new range of
sheets between them.
Delete an endpoint If you delete Sheet2 or Sheet6, Excel adjusts the
calculation to accommodate the range of sheets between them.
I'm not sure if the above works with renamed worksheets, i.e. Smith, Jane
instead of Sheet23, but I suspect it will follow the order that the
worksheets are displayed in the workbook...
HTH,
James Cox