Disclaimers

FlowSheet is a work in progress; I am showing it to my friends in its present imperfect form in order to gather their helpful suggestions on what to improve first. Here are some known issues:

1. Crashes

   FlowSheet is guaranteed not to affect your Excel files or your computer. There is a slight chance it will affect your browser, but in that remote case just restart it. But FlowSheet itself may not "work," i.e. the server may refuse to process your spreadsheet. I know of one way this can happen: if the sheet-names in your workbook contain math-like characters (for example, a sheet called 'Revenue High' is fine, but a sheet called 'Revenue - High' is not). When you find other examples of spreadsheet which won't get processed, feel free to send me a copy (duly sanitized) so I can try to reproduce and fix the problem.

   There can also be problems with large files (problems I am working on now): a large spreadsheet (say 300kb or more) may take so long to load that the browser times-out, or fills the available capacity of the Java process on your computer (the "heap size").

2. What you need

   You must have spreadsheets written in Excel format, and you must have a browser which can display a Java Applet.

3. Security

   Spreadsheets are often highly confidential, sensitive information, and the more important it is to understand a spreadsheet, the more cautious people are about uploading them to remote servers.

   We will not keep, use, publish, reveal, or disclose your data in any way, and will make every effort to prevent others from doing so.

   At the moment the FlowSheet server is practically secure, but not perfectly so. Files are uploaded to a temporary file with a random name, and a new temporary file is created, also with a random name; all files are removed overnight. So it would be exceedingly hard (although not technically impossible) for a stranger to guess the name of your anonymized file and read it himself during those few hours it exists.

   If this possibility still bothers you, feel free to change the numbers in your spreadsheet, remove the headers, or otherwise render its information useless or worse.

4. Printing

   Your browser's "Print" command will not print the FlowSheet you see... which is just as well, since a FlowSheet image may be larger than the visible window, and the printer might try to either shrink it or fit it onto several adjacent pieces of paper.

   The best solution is to display the desired portion of a FlowSheet and take a screen-grab (e.g using ctrl-PrintScrn in Windows, then "Edit-->Paste as new image" in a photo editor)... that image can be saved, rescaled, printed, etc. Once you've done it once, this process is actually faster than printing, and gives you digital images you can use in presentations.

5. Availability

   FlowSheet is provided as a service over the internet (like Google or eBay). The good news is that you don't need to install anything on your computer; the bad news is that any failure of your internet connection, the FlowSheet server, or the latest version of code residing on the server is enough to interrupt the service. There are no guarantees for performance, accuracy, or anything else (at least, not until I get paid for them).

6. Functions

   Excel has far more functions than FlowSheet can display right now. At the moment FlowSheet only displays five functions in a visually sensible way: addition, subtraction, multiplication, division, and negation. Other functions will be added as time permits... vote for your favorites!

7. Units

   Each type of number in FlowSheet has a different color: dollars in green, percent in pink, and so on. All FlowLines of the same color can be visually compared, i.e. a line twice as wide means the number is twice as big. FlowSheet automatically tries to discover which numbers should be grouped and compared this way (i.e. given the same color), but the process is imperfect, and you may discover examples of numbers which ought to be colored the same but aren't, or vice versa. I'm working on improving it, and suggestions are welcome... sorry.

8. Consistency and Language

   I want to make the visual language as clear as possible, which means it may change from time to time... a symbol, color, or even concept may be used differently in the future, so I can't guarantee a consistent appearance to FlowSheets, at least not for now.

   This is a new visual language, and history shows that most invented languages (like Esperanto) don't get adopted, no matter how "sensibly" they were designed. I firmly feel that there is a need for some visual language for algebra, so if not the FlowSheet language then something else even better. If you have ideas or improvements to help get there, let me know.

9. New features

   FlowSheet is only the first of many possible ways of making spreadsheets easier to understand. It would be unwise to announce such new features here, but they will come, and I would be delighted to hear your own ideas.