Network Working Group J. Lines Request for Comments: xxxx 1 March 1996 A MIME content type for 'tagged' partially structured data Status of this Memo This memo describes an experimental protocol for the Internet commu- nity. Discussion and suggestions for improvement are welcomed. Dis- tribution of this memo is unlimited. Overview and Rationale The existing MIME content types provide for the transfer of informa- tion intended to be read by a human being, or viewed as an image, or played as a sound, and while information targeted at a specific application is conveyed by the application types. This document describes a system for organising information as a series of groups of records where each record consists of an identi- fying tag, followed by the data for that record. This document does not describe the valid tag values, but provides an overall framework for creation of different tag types. There are many pieces of information which are carried around the Internet at present which are often manually entered into applica- tions due to the absence of standard ways of exchanging such informa- tion in an application-neutral way. For example if I am part of a group of Sun users who wish to be informed that a meeting will take place at some particular time then a specially formatted mail message will enable recipients of the mes- sage to put the information directly into Sun calendar manager. Many LAN based mail systems have similar facilities, provided everyone is using the same set of products. At present information about events is available across the Internet in mailing lists, News groups and Web pages but has to be transposed by hand into electronic diaries. Similarly a MIME type to describe the actions put on the attendees of a meeting which could be attached to the minutes and read into their todo lists would save much unnecessary retyping. Events, actions and much more can be exchanged using the tag type system described below. Lines FORMFEED[Page 1] RFC xxxx The Tag MIME type 1 March 1996 Design considerations In order to be useful across the wide range of systems used on the Internet the information within a tagged type should be comprehensi- ble to someone with no specialised reader software, in much the same way as a MIME text/plain message does not require a specialised mail reader. It should be possible to create the information with a normal text editor so that specialist software is not required for creating information. There should be few restrictions on the actual data which may be transfered. In particular it is desireable to be able to preserve the formatting of a block of text, rather than have it treated as a string of words. Tag stream format A tag stream looks like a series of items of the form Tagname: value or Tagname:: End_label several lines of text End_label In the first format the data associated with the tag is the contents of the line following the colon, except that a single leading space is not considered part of the data. (For particular applications leading spaces may not be important in any case). In the second format the data is all the lines down to, but not including the End_label. Any non-whitespace printable ASCII string may be used for the End_label, but the use of a single period is not recommended. The first tag in the file will be of the form Tag-tagtype-version: n.nn Tag type registration The formal description of a particular tag type is contained in a file which is itself in tag format. The MIME type tag/dsc is used to exchange tag file descriptors. New tag descriptions or updated versions should be Lines FORMFEED[Page 2] RFC xxxx The Tag MIME type 1 March 1996 registered according to the procedures described in RFC1590. Discussion The machine readable definition of tag types enables suites of programs to be created which can process tag streams without needing to understand the specific application they are used for. They can be used to filter attachments before they are fed into an application, or presented to the reader. Security Considerations The ability to exchange data between applications through an open specification should improve security overall. Where any tag type contains data which may carry its own security risks that should be discussed in the information which relates to the particular tag type. Author's Address John Lines 52, North Hinksey Lane, Oxford, OX2 0LY Phone: +44 1865 988379 Email: john+tag-mime-type@paladyn.org Lines FORMFEED[Page 3]