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

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 cannot 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

- Related Packages
  Package
  Description
  org.apache.sis.metadata.iso
  Root package for ISO 19115 metadata about resources (data or services).
- Classes
  Class
  Description
  AbstractParty
  Information about the individual and / or organization of the party.
  Citations
  A set of predefined 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.