Spreadsheet 2000, S2K for short, featured a unique way of building
complex spreadsheets from a number of simpler ones containing only
input or output data. This contrasts with the traditional spreadsheet
model, where inputs, calculations and outputs are all placed into a
single sheet and cannot be easily differentiated. For instance, if one
wants to add two columns of three numbers, under a normal spreadsheet
one would type the two sets of values into columns, say A and B, and
then into C type the formula =A1+B1, which would appear on-screen as
the results. The formula is then copied into the other cells in C. A
user looking at the sheet would simply see three columns of numbers,
and has no way to differentiate which values are the inputs and which
the outputs.
