You can add additional local variables to the list at the bottom of the data area, such as hidden constants you want to refer to in your formulas.
You can override the variable ses--symbolic-formulas to be a list of
symbols (as parenthesized strings) to show as completions for the '
command. This initial completions list is used instead of the actual
set of symbols-as-formulas in the spreadsheet.
For an example of this, see file etc/ses-example.ses.
If (for some reason) you want your formulas or printers to save data into variables, you must declare these variables as buffer-locals in order to avoid a virus warning.
You can define functions by making them values for the fake local
variable eval. Such functions can then be used in your
formulas and printers, but usually each eval is presented to
the user during file loading as a potential virus. This can get
annoying.
You can define functions in your .emacs file. Other people can still read the print area of your spreadsheet, but they won’t be able to recalculate or reprint anything that depends on your functions. To avoid virus warnings, each function used in a formula needs
(put 'your-function-name 'safe-function t)