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

package org.apache.sis.metadata.iso.maintenance
Information about the frequency and scope of data updates. 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 `├─` Maintenance information `├─` Scope `└─` Scope description Code list `├─` Maintenance frequency `└─` Scope code | Maintenance information `├─` Maintenance frequency «code list» `└─` Scope `├─` Scope code «code list» `└─` Scope description

## 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. Noticeable exceptions to this rule are union structures, for which only one property can be non-empty in the same 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
  DefaultMaintenanceInformation
  Information about the scope and frequency of updating.
  DefaultScope
  The target resource and physical extent for which information is reported.
  DefaultScopeDescription
  Description of the class of information covered by the information.
  LegacyFeatureType
  Deprecated.
  To be removed after migration to GeoAPI 4.0.