icon file format (ICO): A file format used for icons in the operating system.
Incremental Change Synchronization (ICS): A data format and algorithm that is used to synchronize folders and messages between two sources.
Information Rights Management (IRM): A technology that provides persistent protection to digital data by using encryption, certificates (1), and authentication (2). Authorized recipients or users acquire a license to gain access to the protected files according to the rights or business rules that are set by the content owner.
informational update: A Meeting Update object that includes a change that does not require attendees to respond again, such as additional agenda details.
initial ICS state: An Incremental Change Synchronization (ICS) state that is provided by a client when it configures an ICS operation.
instance: A unique publication of data for a category (4). It enables a publisher to publish data for the same category multiple times. An example is a publisher who uses two different endpoints (5) to publish data. These endpoints can publish the same category. However, each endpoint requires a different instance number to be considered a distinct publication by the server (2). An instance number is provided by the publishing client.
instant messaging: A method of real-time communication over the Internet in which a sender types a message to one or more recipients and the recipient immediately receives the message in a pop-up window.
Integrated Services Digital Network (ISDN): A high-speed digital technology that uses existing telephone lines to provide Internet access and digital network services.
internal identifier: (1) An integer that uniquely identifies any item in a term store.
(2) A Folder ID or Message ID, as described in [MS-OXCDATA].
Internet Message Access Protocol - Version 4 (IMAP4): A protocol that is used for accessing email and news items from mail servers, as described in [RFC3501].
Inter-Personal Mail (IPM): Typical user messaging items, such as email and calendar items.
interpersonal messaging subtree: The root of the hierarchy of folders commonly visible in a messaging client. This includes mailbox folders (such as the Inbox folder and Outbox folder) and user-created folders, including user-created public folders.
item: A unit of content that can be indexed and searched by a search application.