## Computergestützte Lehre der Makroökonomik

### Probleme der Darstellung bei einzelnen Browsern

#### Opera

Die Version Opera 9.0 stellt den Text korrekt dar. Einige ältere Versionen haben Probleme mit den mathematischen Sonderzeichen.

#### Firefox/Netscape

Firefox 2.0 hat keine Schwierigkeiten, den Text fehlerfrei widerzugeben.

#### Konqueror

Konquerior 3.4 kann einzelne mathematische Symbole nicht richtig widergeben, z.B. das Identitätszeichen oder den Äquivalenzpfeil. Eventuell wird auf den falschen Symbol-Font zugegriffen.

#### Internet Expl*der

Zumindest für die jüngeren Versionen sind mir keine Darstellungsprobleme bekannt.

#### Ältere Hinweise zur Software TTH (TEX to HTML)

TTH translates TEX into standard HTML and takes account as far as possible of the idiosyncrasies of the major browsers. Nevertheless, there are several problems that are associated with the browsers. Authors and publishers should recognize that these are not TTH bugs.

### 1  MacIntosh browser font problems

The characters with codes higher than 127 in the Mac fonts are in a different order from the standard ISO-8859-1 (sometimes called ISO Latin-1). If Netscape or IE on Macs have their document encoding set to the standard, then in versions 3 onwards they are programmed to access the glyph where they think the corresponding accented Latin character will be in the Mac font. This is fine if one really wants an accented Latin character. However, for mathematics, using the symbol font (which is ordered the SAME on the Mac as on other platforms) the result is that one gets the wrong symbol glyph. This is a particular problem with large delimiters. The fix is that the Mac browser must be set to use the Options/Document-encoding MacRoman". This tells the browser not to do the permutation to access the accented Latin characters in the Mac places; hence, for eight-bit characters, it accesses the symbol font correctly. This would break the Latin accented characters except for the fact that (most current versions of) the browsers still access characters in the Mac order if they are specified numerically using the HTML syntax &#???;". So TTH documents will in most cases display both accented characters and symbols correctly on Macs if the document-encoding is set to MacRoman.

In addition, NS4.0 has under Edit Preferences Fonts a choice between use document fonts'' and use my fonts overriding document''. You need to set use document fonts''. This necessity is obvious if you think about it. You can make any document into garbage by specifying your own font (e.g. Greek or Cyrilic) that happens not to be what the document is written in. The same is true for the symbols of mathematics. The reader must permit the document to specify the font. Browsers should always set use document fonts'' as the default.

In summary, you might want to tell people viewing your documents to set their browsers to View Encoding MacRoman, and Edit Preferences Fonts Use-document-fonts (NS 4.0).

### 2  Netscape Composer

Netscape Composer (in Netscape Communicator 4.0 on) is too clever for its own good. If you run an HTML document produced by TTH through Netscape Composer, all sorts of internal translations are performed that are detrimental to its eventual display. For example, if you subsequently save the document with the usual encoding set (Western), the eightbit codes that work with Macs are replaced with HTML4.0 entities such as [&]ograve; or [&]pound;. This effectively breaks the document for viewing on Macs because it undoes everything just explained. Even if you use User-Defined encoding, which prevents this particular substitution, Composer will rearrange the document in various ways that it thinks are better, but that make the display of the document worse. The moral is, don't run TTH documents through Netscape Composer. You therefore cannot use the publish'' facility of Composer. Transfering the document to the server with plain old ftp will keep it away from Composer's clutches.

[Unconfirmed reports indicate that P*gemill has problems of the same type.]

### 3  X font problems

Symbol fonts are not normally enabled for Netscape running under X, because of the way Netscape groups its fonts. A fix for this is to install some aliases in the fonts directories or else to add a line to your .Xdefaults file. See http://hutchinson.belmont.ma.us/tth/Xfonts.html. You might want to put these notes on your site for people viewing your documents.

Netscape.documentFonts.sizeIncrement: 10
Netscape.documentFonts.xResolution*iso-8859-1: 100
Netscape.documentFonts.yResolution*iso-8859-1: 100

to your .Xdefaults. Then do a xrdb ~/.Xdefaults and restart Netscape

A font rendering problem exists for small size single-symbol overbar in the Xfree86 server. The overbar symbol may or may not appear, depending on the direction in which its window uncovered. (Yes, this is a really bizarre bug but can be demonstrated with the xfd program.) It is strictly not a Netscape bug but an X-server, or perhaps font, bug. This symbol is used by TTH only as a fall-back for \bar in situations like in-line equations where it can't render the construct using tables.

### 4  Opera

I am not able to fix a similar problem for Opera running under X. Opera does not show any symbols of the Adobe symbol font.

### 5  Internet Expl*der

IE 4.0 renders nested sub- and superscripts wrong under Wind*ws 95/8 so that for example the HTML x<sup>n<sub>i</sub></sup> is rendered as if it were x<sup>n</sup><sub>i</sub>. Here is the first form: xni to test your browser. Tests on Win 3.1 with IE 3.01 show no such problem. Obviously this is a fairly serious bug for mathematics that ought to be fixed by the browser programmers. [Let MS*ft know if you observe it, so that plenty of people are complaining and they might fix it.]

### 6  Printing

In Netscape 3.0 and 4.x under X, for example, the printing fonts are hard coded into the browser and the font-changing commands are ignored when printing. For that reason, visitors viewing TTH documents will often not be able to print readable versions of documents with lots of mathematics. This problem could, and should, be fixed in the browsers. However, if you want your readers to be able to print a high-quality paper copy of the file, then you probably want to make available to them either the TEX source or a common page-description format such as Postscript or PDF. Since HTML documents download and display so much faster and better than these other formats on the screen, TTH's translation provides the natural medium for people to browse, but not necessarily the best medium for paper production.