Learn more about the concepts behind the DAD Index and the metadata it uses.
DAD Metadata
File types currently supported:
Documents:
• DOC
• DOCX
• ODP
• ODS
• ODT
• PDF
• PPS
• PPT
• PPTX
• RTF
• TXT
• XLS
• XLSX
Music:
• AAC
• MP3
• OGG
• WAV
• WMA
Video:
• AVI
• FLV
• MPEG
• MPG
• WMV
Images:
• BMP
• GIF
• JPEG
• JPG
• PNG
DAD Metadata baseline:
The DAD metadata baseline is designed to have four levels of data.
First priority for the DAD metadata baseline was the UK eGovernment Metadata Standard (eGMS), which is a metadata standard published by the Office of the e-Envoy to define how metadata should be applied to government resources. This is itself a Dublin Core Application Profile which provides a conceptual framework/set of rules, a "core" vocabulary/set of terms and a set of specifications for representing or encoding DC metadata descriptions in various formats. eGMS and Dublin Core were selected to ease subsequent interoperability and interfacing with other applications and web services. The DAD metadata baseline uses a subset of the eGMS as standard although all eGMS tags can be added if required.
The second priority was metadata as used in commonly available applications such as iTunes and Windows, where this metadata was not already covered by the eGMS.
The DAD metadata baseline was then enriched through media specific metadata including:
• EXIF: Exchangeable Image File Format - found in JPG, TIFF, PNG, MIFF, HDP and PSP images and TIFF-based RAW images.
• IPTC: International Press Telecommunications Council and the Newspaper Association of America Information Interchange Model - found in JPG, TIFF, PNG, MIFF, PS, PDF, PSD and DNG images.
• XMP: Extensible Metadata Platform - embedded in many different image file types including JPG, JP2, TIFF, GIF, EPS, PDF, PSD, IND, PNG, DJVU, SVG, MIFF, DNG and a variety of proprietary TIFF-based RAW images, as well as MOV, AVI, ASF, WMV, FLV, SWF and MP4 videos, and WMA and audio formats supporting ID3v2 information.
• ICC: International Color Consortium (ICC) - found in JPEG, TIFF, PDF, PostScript, Photoshop, PNG, MIFF, PICT, QuickTime and some RAW formats.
• Photoshop tags: Found in PSD and PSB files, also as embedded Photoshop information in many other file types (JPEG, TIFF, PDF, and PNG).
• ID3 tags: Found in MP3, MPEG, AIFF, OGG, FLAC, APE and RealAudio files.
The DAD metadata specification also has its own tags which have been developed to satisfy the requirements of the DAD application, data sharing and the wider semantic desktop. Examples include: Backup (indicates whether the file in question is a DAD backup copy), BeenBackedUp (indicates the file has been backed up by another DAD instance), and SendDuration (allows the transfer of large files between DAD instances to be monitored).
Note: Many of the metadata elements are not required for particular DAD instantiations, although all can be made available if required.
Future Steps:
The next steps will be associate metadata from different sources (e.g. from various web services) with the metadata from the semantic desktop. There are three levels of complexity of metadata association that are being explored:
• Duplication - the metadata is identified as belonging to the same object; multiple sets of metadata are maintained
• Correlation - the metadata is identified as belonging to the same object; the highest quality set of metadata is retained with the lower quality being discarded
• Fusion - the metadata is identified as belonging to the same object; a new set of metadata is created based on elements from all metadata sources; the original metadata sources are then discarded