KeyView 24.4
KeyView Filter SDK .NET Programming Guide

# Metadata Elements

This section explains how to process metadata elements using the KeyView API.

## Standardized Elements

When KeyView understands the meaning of a metadata field in a document, it outputs that data in a standardized element - a `MetadataElement` object where:

- the `IsStandard()` method returns `true`.
- the `StandardKey` property contains the standard key, which indicates the meaning of the element. For a list of standardized keys, see Standardized Metadata Elements. The standard key will not be equal to `MetadataKey.Other`.
- the `Key` property contains a string that is uniquely determined by the standard key. If you are handling the value of a standardized element based on its standard key, you can ignore this value. It is provided so that standardized elements can optionally be handled in the same way as non-standardized elements.
- the `HasStandardAlternative` property is `false`.
- the `IsSuperseded` property specifies whether this element has been superseded, meaning that this element exists only to preserve backwards compatibility. An element can be superseded to fix issues with the key or value type. When this property is `true`, the same metadata is available through an improved `MetadataElement` in the same `Metadata` object.

Each standardized element is guaranteed to occur at most once in the metadata output. For example, a `Metadata` object will contain zero or one `MetadataElement` objects with the standard key `MetadataKey.Title`. To get a specific standard element from a `Metadata` object, pass the standard key to the `Find()` method.

## Non-standardized Elements

Non-standard elements represent native metadata fields. Some non-standard elements might have been used to create a standardized element, and therefore have a standardized alternative. User-created metadata fields, and fields that are unique to one file format, are usually available only as non-standard elements. For a non-standard metadata element:

- the `IsStandard()` method returns `false`.
- the `StandardKey` property is `MetadataKey.Other`.
- the `Key` property contains a string representation of a field's key. If a field key exists in the document, that value is returned. Otherwise, KeyView generates a value.
- the `HasStandardAlternative` property specifies whether the element has a standardized alternative. When this property is `true`, this element contains metadata that also exists in a standardized element in the same `Metadata` object. The standardized element might present the metadata with different units.
- the `IsSuperseded` property specifies whether this element has been superseded, meaning that this element exists only to preserve backwards compatibility. An element can be superseded to fix issues with the key or value type. When this property is `true`, the same metadata is available through an improved `MetadataElement` element in the same `Metadata` object.

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Version 24.4 | Last updated September 2024

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Product: IDOL KeyView 24.4

Topic Title: Metadata Elements