1. Introduction
Contents of DED 0.2
A designer is the kind of ADP tool that lays its content out as a form-based visual layout in which nothing is connected (terminology). A tool engineer specifies a designer type in DESL. DED, the Designer Definition Language, specifies how one document a user created of a designer type is stored: a DED definition. A DED definition is a file that says which version of DED it is written in and which designer type it was made with, and holds that designer type's model beside it.
DED says what the documents of all designer types hold; DESL says what one designer type's documents hold; FBL says how a body is read and written. A designer type's DESL specification names FBL bindings (DESL section 5), and those bindings read the definition's body into the model of the type's metamodel and write each edit back as splices, so a user's file keeps its bytes wherever nothing changed. DED adds the one thing that all designer types share: the envelope of section 2, by which any host can tell a designer's document from any other file and knows the designer type to open it with, without a registration.