Glossary

Extensible Metadata Platform
XMP

XMP standardizes a data model, a serialization format and core properties for the definition and processing of extensible metadata embedded into popular image, video and document file formats (JPEG and PDF…). Although metadata can alternatively be stored in a sidecar file, embedding metadata avoids problems that occur when metadata is stored separately [adxmp].

See also

International Press Telecommunications Council
IPTC

It is a consortium of the world’s news agencies, other news providers and news industry vendors and acts as the global standards body of the news media.

The IPTC defined a set of metadata properties that can be applied to images, part of a broader standard developed in the early 1990s and known as the IPTC Information Interchange Model (IIM).

See also

IPTC Information Interchange Model
IPTC IIM

The IIM standard defines for each field for what purposes it may be used and how the value is stored as binary data. It is still in use, mainly by “IPTC Fields” for photo metadata. Metadata elements of IIM are quite well-known as “IPTC fields” in the “IPTC header” of digital image files.

The Extensible Metadata Platform (XMP) has superseded IIM’s image file header structure, but the properties of the IPTC Core are synchronized between the technical structures of XMP and IIM by a vast majority of imaging software.

See also

Resource Description Framework
RDF

The Resource Description Framework is a method to describe and exchange graph data. It was originally designed as a data model for metadata by the World Wide Web Consortium (W3C).

See also

sidecar files
sidecar
.nksc

File used to save image adjustments. This file may be in a folder or within the same folder as the original image. Because changes are not applied directly to the original image data, pictures can be edited repeatedly with no loss in quality. Sidecar files are also used to store labels, ratings, XMP/IPTC metadata, and other data in addition to image adjustments.

XMP Packet

An XMP packet is a set of XMP metadata properties. Each property has a name and a value. Each property name in an XMP packet shall be unique within that packets [adxmp1]. An XMP Packet is serialized using a subset of the RDF metadata syntax. A single XMP packet shall be serialized using a single rdf:RDF XML element.

References

[adxmp]

Adobe Developer, Overview of XMP technology,

[adxmp1]

Adobe, XMP Specification Part 1, pp. 5-17

[IIMv4]

IPTC, Information Interchange Model Version 4, pp. 11-13, pp. 24-44