Information:  - Web Distributed Authoring and Versioning (WebDAV) is an extension of the Hypertext Transfer Protocol (HTTP) that allows clients to perform remote Web content authoring operations. A working group of the Internet Engineering Task Force (IETF) defined WebDAV in RFC 4918.  - The Calendar and Contacts Server project is an Apple developed standards - compliant server implementing the CalDAV and CardDAV protocols . It provides a shared location on the network allowing multiple users to store and edit calendaring and contact information . The server was publicly released during Apple 's Worldwide Developers Conference on August 7 , 2006 as iCal Server and Address Book Server . The server , named `` caldavd '' , is a daemon background service . It has been ported to non-Apple computer platforms . It is currently possible to install it on FreeBSD and several flavours of Linux . The server is written in the Python programming language with the Twisted framework , and uses an SQL database for storage of calendar data .  - iCalendar is a computer file format which allows Internet users to send meeting requests and tasks to other Internet users by sharing or sending files in this format through various methods. The files usually have an extension of codice_1. With supporting software, such as an email reader or calendar application, recipients of an iCalendar data file can respond to the sender easily or counter-propose another meeting date/time. The file format is specified in a proposed internet standard (RFC 5545) for calendar data exchange.  - Calendaring Extensions to WebDAV, or CalDAV, is an Internet standard allowing a client to access scheduling information on a remote server. It extends WebDAV (HTTP-based protocol for data manipulation) specification and uses iCalendar format for the data. The access protocol is defined by RFC 4791. It allows multiple client access to the same information thus allowing cooperative planning and information sharing. Many server and client applications support the protocol. Extensions to CalDAV for automated scheduling are also standardized, as RFC 6638.  - In computer network engineering, an Internet Standard is a normative specification of a technology or methodology applicable to the Internet. Internet Standards are created and published by the Internet Engineering Task Force (IETF).  - A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically days, weeks, months, and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record (often paper) of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.    Given the information above, choose from the list below the object entity that exhibits the relation 'instance of' with the subject 'calendar and contacts server'.  Choices: - calendar  - computer  - computer network  - designation  - engineering  - exchange  - extension  - file  - file format  - format  - group  - information  - internet  - internet standard  - list  - meeting  - network  - paper  - planning  - server  - sharing  - single  - software  - time
software