A user has an IBM PC with LocalTalk PC Card and is running WordStar
Professional 4.0. He wants to emulate an Epson printer using the
LaserWriter program, without having to modify existing documents. His
question concerns how the international character sets 1 and 2 produce
diphthongs (for example, the ae character).
Diphthongs, like AE or OE, are part of the standard LaserWriter character
set (see page 255 of the PostScript Language Reference Manual from Adobe
Systems Incorporated, published by Addison-Wesley, ISBN 0-201-10174). The
standard LaserWriter character set and the unencoded character set can be
mapped to a single font (see pages 254 and 255 of the "PostScript Language
Reference Manual"). The symbol set (pages 256 and 257) cannot be mapped
together with the standard LaserWriter character set or the unencoded
character set into a single font.
Here are three questions with answers concerning dipthongs and fonts:
1) Does the Courier font include diphthongs?
Diphthongs are part of the standard LaserWriter character set and are
included in the Courier font. Using the standard character set, the
diphthongs (AE, OE, ae, and oe) are ASCII codes 225, 234, 241, and 250,
respectively.
These characters are mapped to new positions using extended
international character sets 1 and 2. Selecting either international
character set 1 or 2 from the LaserWriter print options for WordStar
documents will allow access to the AE and ae diphthongs at ASCII
locations 146 and 145, respectively. See page 91, "Printing from
extended character sets" in Appendix A. The OE and oe characters are in
the same locations and can be accessed with the same codes as in the
standard character set.
2) If the answer to number 1 is no, from which character set do the
diphthongs come if one is printing in Courier with international 1
extended characters?
As stated in the answer to question 1, diphthongs are available through the
Courier font.
3) If the answer to number 2 is a proportionally spaced font, like Helvetica
or Times, how does the use of diphthongs from proportionally-spaced fonts
from another font fit with your reasoning that symbol font characters cannot
be remapped in this manner, because they are from another font and are
proportionally spaced?
Neither Helvetica nor Times fonts, containing standard or unencoded
characters, can be mapped with Symbol set characters due to the limitation
restated in the question. This is because the Adobe PostScript command,
which is used to merge character sets into a single font definition, is
limited to the Standard LaserWriter and unencoded character sets.
Symbol set characters cannot be used with proportionally spaced fonts even
though both use proportionally spaced graphic images because there is only
one set of commands used for merging character sets into a font.
The limitation is not in the use of the commands (as in the hypothetical
case of mapping proportional characters with proportional symbols), but in
Adobe's limiting implementation of their commands. This causes the
remapping not to work with Symbol set characters and standard LaserWriter
and unencoded character sets. This means that standard characters and
unencoded characters are accessible within Helvetica and Times. Symbol set
characters remain inaccessible from the same remapped font. Note: Character
sets are not fonts. Fonts are the graphical images to which the character
sets are mapped.