Given a source of saved Gnumeric data, Spreadsheet::ReadGnumeric parses it and
returns the result in the same format as Spreadsheet::Read. In fact,
Spreadsheet::Read has a few more bells and whistles, such as transposing the
resulting sheets and providing an object-oriented interface to the resulting
data, so it may be easier to access this module through Spreadsheet::Read, even
if you only want to parse Gnumeric data.

Note that Gnumeric only saves raw cell values, and not their formatted versions.
In particular, Gnumeric saves formulas, and not formula values, never mind
formatted formula values.