Data structure used for implementing spreadsheets

Question

What is the data structure used by spreadsheets program like ms-excel?

Answer 1

Maybe, probably, a sparse matrix:

http://en.wikipedia.org/wiki/Sparse_matrix

Answer 2

Possibly a multi-dimensional array.

Answer 3

While it is not exactly Excel, Open Office's Spreadsheet program is open source. It's a fairly large code base but nevertheless giving it a peek might give you a better understanding of how such an application is implemented:

http://contributing.openoffice.org/programming.html

Answer 4

I expect it to use many.

For example, an AST to recalculate formulas (see this question).