Release as    [Indigo]<Interscript>Std>Interscript-IG.tioga, .press
    Draft        [Indigo]<Interscript>DraftStd>Interscript-IG.tioga, .press
    Last edited    By Mitchell on February 28, 1983 10:42 pm
LIMITED DISTRIBUTION: FOR XEROX INTERNAL USE
Interscript  Implementor's  Guide
    Version 1.0/March, 1983
Abstract
XEROX
PALO ALTO RESEARCH CENTER
COMPUTER SCIENCE LABORATORY
3333 Coyote Hill Road / Palo Alto / California 94304
Contents
1. Introduction
2. Internalization
3. Externalization
4. Editing
5. Rendering
    With these definitions, we can now give some conservative rules for editors in treating parts of documents corresponding to spans 
    in a script:
        It's OK for an editor to display a span if
            it understands at least one of its tags.
        It's OK for an editor to edit within a span if
            it implements all of its tags, and either
                (a) doesn't remove any of them, or
                (b) also understands all tags of its parent.
        It's OK for an editor to copy a span if
            it understands all the tags of the span's new parent,
            no labels are moved outside their scope, and
            the two environments have the same bindings for all attributes that the editor either
                doesn't understand, or
                knows can't be relevant anywhere in the span or its subspans.
        It's OK for an editor to delete a span if
            it understands all the tags of its parent.
    [Less stringent rules will suffice if the document is merely to be viewed, rather than edited, using the original editor.]