From Ascgroup

Isn’t using an Excel® spreadsheet equivalent to using the TF!© software?

While the TF!© software requires Excel® to operate, the TF!© software contains pre-established protected formulas which requires users to only be able to input data rather than to also manipulate the data with formulas created on their own. The pre-established input format and protected formulas produce consistent, error-free output results allowing an apples-to-apples comparison amongst different solutions presented by different bidders using the TF!© software. Without input driven software such as TF!©, many bidders present their data in Excel tables without performing substantive calculations, which is of minimal use to the evaluation and can be of questionable accuracy.