After Excel introduced the dynamic array support, files produced with the older Excel versions have formulas that may be displayed with @ in some contexts. For example a file that had the following:

=SUM(IF(A1:A10=1, B1:B10, 0))

Will be displayed like so:

=SUM(IF(@A1:A10=1, B1:B10, 0))

This is done in order to preserve the behavior of the files created in older versions of Excel.

The files created by SpreadProcessing are also treated by Excel as if they are created by pre-dynamic array Excel. Please, introduce support for the new behavior.