You need only to choose a document listed under 'Library' on the left and to click it. The use is simple and intuitive: you click onto a text or number (normally in blue color: see below) to modify the data shown in it. You only need to know the color code for text boxes and a single instruction to follow: see below.

Sheets marked by a 'X' in the menu are visible, but cannot be modified nor recalculated. To use them you need to make a copy in your private space as follows: 1-Register (or log in if already registered), 2-Open the desired sheet in the main window, 3-Choose 'Tools' in the menu, then 'Actions on sheets', then 'Copy sheet...'. After reloading, the sheet in the main window is a private copy that you may modify and recalculate.

blue : this field must be set manually (you'll normally interact only with this color).
green : this field contains a formula that calculates a proposed or default value: you may set it manually if you want a different value.
light blue : this field was based on a formula, but has been set manually (formula may be restored at any time).
violet : this field is based on some external data that is not available at the moment; you'll normally have to set it manually.
black : this field is based on a formula and you normally should not set it (though you can).
red : the value calculated for this field is not within some expected bounds (this normally indicates a negative result for the calculation).
There are a few more codes, but you should first of all try it: it's easier to do than to say!

Data shown in the sheet are rounded, to make them more readable, however in the calculations the maximum available precision is used. To see the value actually used in the calculation for a specific item you may click onto it: that value will be visible in the dialog box that is opened.

To save the results of the calculation, if you don't have a copy of the file, you may print the sheet: you do this with browser's commands, preferably by right clicking onto a white region of the sheet, to print only the relevant frame. Please ask if your printer represents the sheet incorrectly.

All formulas used for calculating displayed results may be viewed (and printed) by clicking on 'Options' -> 'Show formulae' in the menu. Square brackets '[x]' are used in formulas to represent data collected from a table contained in the references onto which the sheet is based (as a function of x, where applicable). Moreover '[f]', where 'f' is a formula, indicates a tabular input as above, where the formula is used by default, where the table does not provide the corresponding value. Instead, the symbol '[#]' indicates a calculation method too complex to be detailed online: more information upon request.

Of course yes! You'll get the necessary directions with the confirmation of the registration or choosing 'More help' under 'Info/News' in the menu .

All sheets are provided in the state 'as is', without any implicit or explicit warranty: all users must choose the calculation method best suited to their problem, and check all results for correctness and consistency. If advised of a mistake or inconsistency, our only duty shall be to make the necessary corrections and advise all users owing copies of the mistaken sheet.