The following terms are specific to this document:
ASCII: The American Standard Code for Information Interchange (ASCII) is an 8-bit character-encoding scheme based on the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that work with text. ASCII refers to a single 8-bit ASCII character or an array of 8-bit ASCII characters with the high bit of each character set to zero.
Attachment object: A set of properties that represents a file, Message object, or structured storage that is attached to a Message object and is visible through the attachments table for a Message object.
body part: A part of an Internet message, as described in [RFC2045].
clear-signed message: An Internet email message that is in the format described by [RFC1847] and is identified with the media type "multipart/signed", or the Message object representing such a message. An important class of clear-signed message, based on a "multipart/signed" format, is the S/MIME clear-signed message, as described in [RFC5751] and [RFC3852].
encrypted message: An Internet email message that is in the format described by [RFC5751] and uses the EnvelopedData CMS content type described in [RFC3852], or the Message object that represents such a message.
globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).
header field: A component of a Session Initiation Protocol (SIP) message header, as described in [RFC3261].
message body: The main message text of an email message. A few properties of a Message object represent its message body, with one property containing the text itself and others defining its code page and its relationship to alternative body formats.
Message object: A set of properties that represents an email message, appointment, contact, or other type of personal-information-management object. In addition to its own properties, a Message object contains recipient properties that represent the addressees to which it is addressed, and an attachments table that represents any files and other Message objects that are attached to it.
MIME body: The content of a MIME entity, which follows the header of the MIME entity to which they both belong.
Multipurpose Internet Mail Extensions (MIME): A set of extensions that redefines and expands support for various types of content in email messages, as described in [RFC2045], [RFC2046], and [RFC2047].
opaque-signed message: An Internet email message that is in the format described by [RFC5751] and uses the SignedData CMS content type described in [RFC3852], or the Message object that represents such a message.
MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.