# Package org.apache.sis.metadata.iso.citation

Reference to the data or service (citation, responsible party, contact information). An explanation for this package is provided in the OpenGIS® javadoc. The remaining discussion on this page is specific to the SIS implementation.
Overview
For a global overview of metadata in SIS, see the `org​.apache​.sis​.metadata` package javadoc.

Package overview
Class hierarchy | Aggregation hierarchy
--- | ---
ISO 19115 metadata `├─` Citation `├─` Citation date `├─` Responsibility `├─` Party `│ ├─` Individual `│ └─` Organisation `├─` Contact `├─` Telephone `├─` Address `├─` Online resource `└─` Series Code list `├─` Date type `├─` Online function `├─` Presentation form `└─` Role | Citation `├─` Citation date `│ └─` Date type «code list» `├─` Responsibility `│ ├─` Party `│ │ └─` Contact `│ │ ├─` Telephone `│ │ ├─` Address `│ │ └─` Online resource `│ │ └─` Online function «code list» `│ └─` Role «code list» `├─` Presentation form «code list» `└─` Series

Unified identifiers view
Apache SIS provides a unified view of all metadata identifiers. This view includes the citation ISBN and ISSN codes, except at XML marshalling time (for ISO 19115-3 compliance). See `IdentifierMap` for more information.
Null values, nil objects and collections
All constructors and setter methods accept `null` arguments. A null argument value means that the metadata element can not be provided, and the reason for that is unspecified. Alternatively, users can specify why a metadata element is missing by providing a value created by `NilReason​.createNilObject(Class)`.

Unless otherwise noted in the Javadoc, all getter methods may return an empty collection, an empty array or `null` if the type is neither a collection or an array. Note that non-null values may be `NilObject`s.

Unless the metadata object has been marked as unmodifiable and unless otherwise noted in the Javadoc, all collections returned by getter methods are live: adding new elements in the collection modify directly the underlying metadata object.

Since:
  0.3

Defined in the `sis-metadata` module

- Class Summary
  Class | Description
  --- | ---
  AbstractParty | Information about the individual and / or organization of the party.
  Citations | A set of pre-defined constants and static methods working on citations.
  DefaultAddress | Location of the responsible individual or organization.
  DefaultCitation | Standardized resource reference.
  DefaultCitationDate | Reference date and event used to describe it.
  DefaultContact | Information required to enable contact with the responsible person and/or organization.
  DefaultIndividual | Information about the party if the party is an individual.
  DefaultOnlineResource | Information about on-line sources from which the dataset, specification, or community profile name and extended metadata elements can be obtained.
  DefaultOrganisation | Information about the party if the party is an organization.
  DefaultResponsibility | Information about the party and their role.
  DefaultResponsibleParty | Identification of, and means of communication with, person(s) and organizations associated with the dataset.
  DefaultSeries | Information about the series, or aggregate dataset, to which a dataset belongs.
  DefaultTelephone | Telephone numbers for contacting the responsible individual or organization.