RFC 2077: The Model Primary Content Type for Multipurpose Internet Mail Extensions | RFC Editor

Skip to content Primary navigationThe RFC SeriesFor AuthorsAbout UsHomeRFC 2077 View as: Plain Text, Compact HTML Info RFC 2077: The Model Primary Content Type for Multipurpose Internet Mail ExtensionsMIMEJanuary 1997. S. Nelson, C. Parks, MitraProposed StandardSubscribe4 subscribed Add to Set Read aloud This RFC was updated, see RFC 9141.Network Working Group S. Nelson Request for Comments: 2077 LLNL Category: Standards Track C. Parks NIST Mitra WorldMaker January 1997 The Model Primary Content Type for Multipurpose Internet Mail Extensions Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Introduction The purpose of this memo is to propose an update to Internet RFC 2045 to include a new primary content-type to be known as "model". RFC 2045 [1] describes mechanisms for specifying and describing the format of Internet Message Bodies via content-type/subtype pairs. We believe that "model" defines a fundamental type of content with unique presentational, hardware, and processing aspects. Various subtypes of this primary type are immediately anticipated but will be covered under separate documents. Table of Contents 1. Overview............................................. 2 2. Definition........................................... 2 3. Consultation Mechanisms.............................. 4 4. Encoding and Transport............................... 5 5. Security Considerations Section...................... 6 6. Authors' Addresses................................... 7 7. Expected subtypes.................................... 7 8. Appendix............................................. 9 9. Acknowledgements..................................... 13 Nelson, et. al. Standards Track [Page 1] RFC 2077 Model Primary MIME Types January 1997 1. Overview This document will outline what a model is, show examples of models, and discuss the benefits of grouping models together. This document will not directly deal with the intended subtypes since those will be covered by their separate registrations. Some immediately expected subtypes are listed in section 7. This document is a discussion document for an agreed definition, intended eventually to form a standard accepted extension to RFC 2045. We are also targeting developers of input/output filters, viewer software and hardware, those involved in MIME transport, and decoders. 2. Definition of a model A model primary MIME type is an electronically exchangeable behavioral or physical representation within a given domain. Each subtype in the model structure has unique features, just as does each subtype in the other primary types. The important fact is that these various subtypes can be converted between each other with less loss of information then to that of other primary types. This fact groups these subtypes together into the model primary type. All of the expected subtypes have several features in common and that are unique to this primary type. To loosely summarize: models are multidimensional structures composed of one or more objects. If there are multiple objects then one object defines the arrangement/setting/relationship of the others. These objects all have calibrated coordinate systems but these systems need not be in the same units nor need they have the same dimensionality. In detail: 1. have 3 or more dimensions which are bases of the system and form an orthogonal system (any orthogonal system is sufficient). This system is specifically defined in terms of an orthogonal set of basis functions [for a subspace of the L^2 function space] over a coordinate system of dimension 3 or more. Note that this does not preclude regular skewed systems, elliptical coordinates, different vector spaces, etc. 2. contain a structural relationship between model elements. 3. have scaling or calibration factors which are related to physical units (force, momentum, time, velocity, acceleration, size, etc.). Thus, an IGES file will specify a building of non-arbitrary size, computational meshes and VRML models will have real spatial/ Nelson, et. al. Standards Track [Page 2] RFC 2077 Model Primary MIME Types January 1997 temporal units. This allows for differing elements to be combined non-arbitrarily. 4. Models can be single objects or composed of a collection of objects. These normally independent objects are arranged in a master/slave scenario so that one object acts as the reference, or primary object, which defines how the other objects interrelate and behave. This allows for the creation of mathematical, physical, economic, behavioral, etc. models which typically are composed of different elements. The key is in the description: these types describe how something "behaves"; contrasted to typical data types which describe how something "is". The inclusion of this "collective" system works similar to the Email system's multipart/related type which defines the actions of the individual parts. Further specification of the model/* subtypes utilizing these properties is left to the subtype authors. With these assumptions: a. the default dimensionality will be spatial and temporal (but any are allowed). b. it is presumed that models will contain underlying structure which may or may not be immediately available to the user. (fluid dynamics vector fields, electromagnetic propagation, interrelated IGES dimensional specifiers, VRML materials and operators, etc.) c. it is assumed that basis set conversion between model domains is lossless. The interpretation of the data may change but the specification will not. i.e. convert the model of the U.S.A. Gross Domestic Product into a VRML model and navigate it to explore the variances and interrelationships. The model has many dimensio