Q1. Why are Numerical Recipes and Cambridge University Press now requiring the plugin?
A1. We are building a unified infrastructure that allows us to deliver all of the following: (i) free content that is in the public domain; (ii) content that is copyrighted, but nevertheless free; and (iii) copyrighted content by subscription. To do this in today's world we must satisfy authors and publishers that their interests are not being completely disregarded. Of course, we must also satisfy users that the infrastructure is workable and efficient.

Q2. Is the plugin safe? Does it contain spyware?
A2. The plugin is developed by FileOpen Systems, Inc. Numerical Recipes Software is a licensee of the technology. FileOpen Systems has been a licensed Adobe Security Partner since 1997. The FileOpen plugin runs only within Adobe Acrobat or Adobe Reader, and only in connection with opening a FileOpen encrypted document. It contains no spyware or malware, leaves nothing running on your machine, and makes no changes in your Windows registry or in system files.

Q3. What does the plugin do? How does it work?
A3. When you open a FileOpen encrypted document, either through your web browser or else a document already downloaded to your machine, the plugin exchanges a few dozen bytes with a web server, using the standard secure web protocol (https or SSL on port 443). In the case of a free document, the exchange simply verifies that it is, in fact, free. In the case of a subscription document, it verifies that you are a subscriber. Generally, this exchange will occur only once every 30 days for each document, and only when you actually open the document.

Q4. What information about me or my machine does the plugin send?
A4. The plugin sends an identifier of the file that you are opening, and an identifier of your machine that was randomly generated when the plugin was first used. No personal information about you or your machine is gathered or sent. Our server does not collect anything that associates your machine with your name, location, etc. The information that we collect is the minimal information that allows us to administer both free and subscription access in a unified way.

Q5. Does the plugin write anything to my machine?
A5. Yes. The plugin creates a directory and stores short (few kB) status files in it. For Windows, it is generally located at "C:\Documents and Settings\[your username]\Application Data\FileOpen\". For Linux or Mac, it is generally located in your home directory as a subdirectory named ".fileopen". You can delete these directories whenever you want. Then, however, the plugin will do web exchanges for every document opened (not just once in 30 days), and it might lose its memory of your machine's authorization for any paid subscriptions that you have. However, it is not hard to reauthorize your machine, if necessary.

Q6. Can I still save the files? print the files?
A6. Yes. The files can be saved, printed, or moved around just like any other PDF file. You'll need the plugin to be installed on any machine on which you want to use them, however. In the case of paid subscriptions, the new machine will also need to be authorized for the subscription. This is easy to do.

Q7. I'm getting pauses or "Stopped" messages. Is this normal?
A7. The first time you open a file, there may be a pause of several seconds after the file is completely downloaded. This tends to be most noticable when the download itself was slow, due to network congestion or a slow internet connection. During this pause time you may see a blank (or, possibly, incompletely drawn) window, or the message "Stopped" or "Done". This is normal. When you subsequently open the same file, either from the web or a downloaded copy, there should be little or no such delay. We are working on technology improvements that will further reduce any delays.

Q8. What if I am not connected to the web?
A8. If you open and save a document locally on your computer, then you'll be able to use that document for at least 30 days whether or not you are connected to the web. You can renew your 30 days by reconnecting to the web and reopening the document.

Q9. Can the FileOpen technology be defeated?
A9. Yes, almost surely. We are not trying to win any anti-hacker prizes. FileOpen is an ordinary, commercial product for ordinary, commercial-level rights management. Defeating it is merely dishonest, not heroic. You might just as well go into a bookstore and steal a copy of the Numerical Recipes book. It is dishonest either way. If too many of our books are stolen, then bookstores won't carry them. If too many Numerical Recipes files are circulated as "warez", then our publishers will never allow us to do another electronic version, or even improve or correct the current one.

Q10. How do I install the plugin?
A10. See the installation instructions page.

Q11. Where can I go for help?
A11. If you are getting blank pages, or messages about a missing plugin, then you don't have the plugin installed. If the installation instructions page doesn't help, have a look at the Numerical Recipes Forum under "Plugin Problems". Someone else might already have solved your problem, or you can post it there to get advice from us or another user.

Q12. Does the plugin work with Mac OSX? with Linux? with FreeBSD? with Solaris?
A12. Although we had a bit of a rocky start with Mac OSX (because of nearly simultaneous changes in the OS and in Adobe's Reader), the plugin now works well with OSX 10.4 (Tiger) and later and Adobe Acrobat/Reader versions 7 and 8. New installation instructions are here. The most seamless experience is with the Safari browser and Adobe Reader 8 (which displays PDF in the browser window).

For Linux, some earlier versions of the plugin did not work properly. That problem is now (hopefully) solved, and new installation instructions are here. You'll need Adobe Reader 7 or later (free). The Firefox, Epiphany, and Opera browsers can be configured to display PDF seamlessly in the browser window. The Konqueror browser displays PDF in an external window.

FileOpen Systems intends to support Solaris with a FileOpen plugin at some future date, see their plugin page. Regrettably there are no announced plans to support FreeBSD. (Wizards: Do you think you could hack the Linux or Intel Mac OSX plugin to work with BSD?)

Q13. What if I pay for a subscription and then can't get the plugin to work?
A13. Don't do it! All of our subscription products have a "try before you buy" feature that let's you install the product and try out sample sections BEFORE you pay for a subscription. Be sure to try out this feature on ALL machines that you might want to use for your subscription before paying! The most abbreviated "try before you buy" is: (1) install the plugin by following these instructions. (2) Verify that you can read this page.