A trigger for buggy Acrobat behaviour

["Melissa O'Neill" <oneill@cs.sfu.ca>]

I believe I have found a cause for buggy behaviour in Macintosh Acrobat
Exchange software when used with ATM Deluxe 4.0 (under System 8.x); this
bug may also manifest itself in other configurations.

In PostScript, it is okay for an encoding to reference a glyph which is
not actually in the font -- doing so is like refering to the .notdef
glyph. However, it appears that such reencoding in PDF files causes
problems for Mactintosh Acrobat 3.01 and/or ATM Deluxe 4.0.

The fix for this problem should be quite easy. PostScript drivers can
change the way they reencode fonts: Instead of using a single encoding
vector, which may include glyphs that aren't in the font, the driver
must arrange to generate a custom encoding for each font -- one that
only references glyphs that actually exist in the font. This process
can be done either by checking the CharStrings dictionary for the font
using PostScript code, or by using the font's TFM or AFM file as a guide
inside the driver). If this step is taken, the problem goes away.

This would explain why LY1 has problems, since it includes dotlessj,
additional f-ligatures, etc., which aren't in many fonts.

Regards,

    Melissa.
    
P.S. I don't claim that this is the only bug in the Macintosh Acrobat
Reader.