An input box consists of three columns in a multi box like layout. The first column shows a list of variables. The second column equal signs '=' and the third column the values of the variables. It can contain one or many variables, each one on a separate row.
In an input box the current value of the variable is shown. By clicking on a value in the input box, the cell will turn into edit mode, so that a new value can be entered or the old one modified. If the variable contains a formula, that will now be shown rather than its result. The cell in edit mode will normally contain a ... button which opens up a full editor window to facilitate creation of advanced formulas. The function of a variable value cell in an input box could very well be compared to that of a cell in a spreadsheet.
