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Re: PostScript (Was: Re: audio, checksums, and trojan horses)

1991-11-16 09:04:01

Ned writes:

| Jim is entirely correct -- in most cases the PostScript level is just about
| the last thing you have to worry about. This is due to the simple fact that
| Level 2 interpreters are hard to come by, and as a result people write
| PostScript code that will work with either Level 1 or 2. Other information,
| like whether or not a color display is needed to display the document
| properly, are much more important. There are, however, no simple ways to
| determine this information and extract it to a small sensible set of
| attributes. The document structuring conventions are fairly complex (the
| syntax is trivial, but there are lots of attributes plus order
| dependencies).
| A dummy application is not quite the right word for the thing that solves 
| this problem, incidentally. This gadget is called a document manager, and 
| it is a fairly well-understood bit of PostScript-ware. Document managers are 
| never essential to the use of PostScript, but when choices between different 
| devices and whatnot must be made, they are essential, and indeed, the only 
| way to go.

I disagree allmost 100% with this. The color thing is not an issue at all.
Device independence is one of the best features (if not the best) of PS.
It will take some time before Level 2 interpreters are common. Therefore
any usage of the L2 features is what needs to be clearly flagged in the 
Content-Type specifier. The rest will be prosessable by the current
interpreters. If the sender makes use of even one L2 feature the content
should be labelled to require a Level 2 viewer.