When a tiddler is retrieved using a text representation it is presented as a UTF-8 encode text/plain file with two sections. The sections are separated by a blank line. The first section makes up headers in a format similar to an RFC 822 mail message:

Each key represents an attribute on the tiddler, or an extended field.

The second section, the body, is the wikitext of the tiddler. In the case of a binary tiddler this will be base64 encoded text.