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From: kevina@apple.com (This space for rent)
Newsgroups: comp.lang.postscript
Subject: Re: font question
Message-ID: <10150@goofy.Apple.COM>
Date: 11 Sep 90 17:01:47 GMT
References: <564@gestetner.oz>
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 26

In article <564@gestetner.oz> graham@gestetner.oz (graham) writes:
> Page 95 of Postscript Language Reference Manual:
> "All unused positions in an encoding vector must be filled with the name
> '.notdef'. Printing one of these unused characters produces no marks on 
> the page and no side-effects".
> 
> Builtin fonts, which use the StandardEncoding vector, do not seem to 
agree.
> Characters that index to a ".notdef" name, seem to cause the same
> side-effect as produced by "space".
> Is this implementaion/version specific ?
> What does the latest documentation have to say ?

Depending on how you interpret "side-effects", the space character fits 
the Adobe definition:  a) it doesn't leave any marks on the page, and b) 
the side-effects talked about probably refer to VM and interpreter state rather than currentpoint (I agree that it is confusing!)  I understand 
that the Redder Book will clarify this for Type 1 fonts and leave the 
behavior of .notdef up to the designer for others.

The reason that .notdef must exist is that most Adobe font types quietly 
substitute it rather than raise an undefined error if a character name 
from the Encoding vector is not found in the CharStrings dictionary.

--Kevin Andresen [kevina@apple.com]
"The first time I read the dictionary I thought it was a poem about
everything."