Arena: Frequently Answered Questions

Why another browser?
Arena's primary purpose is to be a testbed implementation of the evolving HTML3 specification. Secondary, we want to make a good GUI browser based on the the W3C Reference Library. The library provides a common platform which will ensure future compatibility on the web. Also, if you are a browser vendor, it will save you time.
What is a style sheet?
HTML was not designed to give authors control over the final presentation of a document. Fonts, color and volume has been the domain of the reader/browser. Many authors want to influence the final presentation, and many readers would like them to. Style sheets provide a way to attache presentation hints to the documents without affecting HTML. This is a much debated issue, and you may want to read more of the background material available.
What is HTML3 ?
To learn more about HTML3 and how it may change the web, take the HTML3 guided tour. Also, a draft DTD is available. The DTD is normally a few steps ahead of the Arena implementation.
How do I specify colors in the style sheet mechanism?
You can either specify colors in hexadecimal RGB values (both 3 and 6 acharacter are accepted, e.g. #F0F, or #FF00FF), or using names that your window system knows.
Using the new style sheet mechanism I don't seem to be able to to control the colors accurately, why?
The style sheet mechanism do not allocate any new colors, but reuses the ones found in the dithering cube. Arena will give you the best approximation available.
How do the style sheets cascade?
The style sheet found in your initial document becomes your personal preferences. It will be applied to other pages, unless the other page has its own style sheet. If so, the two styles will be merged with preferences given to the latter document. Currently, merging means picking the first value found for a particular parameter. In the future, we want to provide a mechanism for selectively overriding and blending parameters in the various style sheets.
Why isn't Arena available for my flavor of unix?
When releasing a new version of Arena, we compile for the platforms available in the CERN park of reference machines (hp, sun, decstations (mips), sgi, ibm rs6000). Unfortunately, several popular platforms are not represented there. We therefore make source code available to volunteers for porting, but these platforms will necessarily be a bit behind. You can find binaries for several more plaforms in the subdirectories.
How do I prevent Arena from going to each time it starts up?
Unless instructed otherwise, Arena will fetch the relevant release page from the server. It's a useful page (that you also can reach through the "Help" button), but you may not want to do this every time. Either, start arena with a URL as an argument (e.g. arena, or set the environment variable WWW_HOME to a URL (in csh: "setenv WWW_HOME").
How do I convert LaTeX maths and tables to HTML3?
Janne Saarela at CERN has written a translator to do this. It's name is math2html and it is freely distributable.
Other translator is written by Marcus Hennecke which only translates tables. It can be retrieved from Stanford.
How can I make HTML 3 <MATH> element start with superscripts or subscripts?
One should place the base inside the <MATH> element as well. If the font of the base is not correct, you can control it with <T>, <B> and <BT> elements. Example: <MATH><T>base</T><SUP>super</SUP> <MATH> is rendered as basesuper
What does the "Bad HTML" message in Arena mean?
If Arena finds HTML errors in the document, she flags it in the upper right corner. (The number in parenthesis is an internal error code, not line number or number of bugs.) In most cases, Arena and other browsers will still be able to show the docuement as intended by the author, but who wants to be seen in cyberspace with a bad HTML flag?
How can I see HTML errors?
If you want to see - and fix - the errors, press the "Edit" button. Arena will start the editor specified in the EDITOR environment variable (or using the "-editor <editor>" option). The raw HTML will be inserted in the buffer along with short error messages camouflaged as comments. You can set the maximum number of errors to be flagged using the -badflags option.

After have been through an edit cycle, you will also see the errors when toggleing the view button.

How can I edit HTML in Arena?
Start the editor as described above. Make your changes, save the buffer, exit the editor and Arena will show you the edited document. To save the file, either press the "SaveAs.." button and type in a file name (no expansions are supported yet), or go into your editor and save the buffer into the proper filename from there.
What are the command line options?
How do I run Arena from behind a firewall? Has it been SOCKSified?
Arena is not SOCKSified, but the CERN httpd proxy server is. Therefore, you can get through your firewall by pointing Arena to a proxy server running on the inside.
How does Arena cache documents?
Currently Arena doesn't cache in memory but uses disk for this. By default, Arena will write fetched documents into /tmp. E.g. http document from CERN's info server will go to /tmp/http/ When exiting, Arena will delete all cached documents and the corresponding directory structure. I.e., the disk cache is not persistant. Yet.

Also, if you run several Arena processes simultaneously on the same machine you may want to specify different cache directories as they will not be able to take advantage of each other's caches. See command line options.

What X11 resources can be set?
We are moving away from the platform-specific X121 resources to style sheets that can roam the web. For a tutorial on writing style sheets, see the draft specification. Note that the syntax described there is the one implemented in version 0.98. If you use an earlier version, see the style sheet examples under the help page.
What hotkeys does Arena support? Why not <space>?
Arrow keys will move you around in the current document. Ctrl + arow keys will take you page up/down and forward/backward in history. Also, the following X11 keys are supported: Page Up (XK_Prior), Page Down (XK_Next), Home (XK_Begin) and End (XK_Home). We have not been supporting some of the other common hotkeys (e.g. <space> for Page Down) because this may conflict with future HTML editing. Enough people have asked for this to make us reconsider.
Why doesn't forms, index searching, hotlists - or other features - work?
Arena'a primary purpose is to be a testbed to HTML3. In order to be so, some things need to work (among them forms), while others (e.g. hotlists) are irrelevant. Arena's secondary purpose is to be a good general purpose web browser. In order to succed, it needs several additional features (e.g. hotlists), but the manpower we can spend on this is limited.
How can I specify external viewers?
Arena supports mailcap files. If you have a file called .mailcap in your home directory with this line in it:

image/gif; xv %s; quality = 0.95

Arena will display all images using the xv program instead of inline. The quality statement is an indicator of how well the application is able to display the data type. The HTTP server may use this information to determine what format to send to you. The default quality is 0.5.

Arena will also look for other mailcap files that the MAILCAPS environment variable points to.

Help! Arena displays all images externally. What's wrong?
You have probably declared an external viewer for GIF images. Arena does not distinguish between inline and "outline" images; if a viewer is defined, it will be used for all images.
Will Arena source code be available?
Send an email to for see the source. There are restrtrictions on the use of the source, but we're working towards liberalization.
How can I make Arena work with proxies?
Arena (i.e. the library) reads the http_proxy environment variable. Using csh, you could say

setenv http_proxy

This is also described in the CERN httpd documentation.

On my sun, Arena can't find any hosts. What's the problem?
Name resolving. Try using "the other" binary, e.g. arena-sun4-4.1.1-lresolv.bin or arena-sun4-4.1.1.bin.
Arena comes up in black and white (or grayscale) on my color screen. Help!
There is probably another application hogging the colors. Try quitting other applications (e.g. Netscape and Mosaic) and restart Arena. Or, you can start Arena with the "-cm" command line option (introduced in 0,98).
I found a bug! How do I report it?
First, check to see if the bug has been reported. You can get to the bug list for the version that you are using by pressing "Help". You may also be told that you need to upgrade.

If you can't find it there, please mail a report to Please remember to state the version of: arena, your OS and your X11 display.

I submitted a bug report, but it still isn't fixed. Why?
We try to answer all reports and indicate a priority/complexity factor. We do not have the manpower to fix/implement all requests immediately. But we hope you enjoy Arena anyway.