It doesn't "know", but if it isn't a named range, the formula will give an error. It should
refer to a multi-cell range (in a single row or column), not to the header cell only (unless you
have only 1 holiday).

On Wed, 23 Jul 2003 13:50:13 -0700, "ChrisG" wrote:

I received a WS with the function NETWORKDAYS being used
as follows

=NETWORKDAYS(BO91,BU91,holidays)-1

where

BO91 = Start Date
BU91 = End Date
holidays = the header cell on a range of dates in another
worksheet.

my questions....How does the function know that holidays
is a range and how can I assess that condition.