UCD describing metadata

Many concepts related to metadata information are not covered by the original UCDs. A good example is trying to describe some data model attributes or FITS headers keywords with UCDs.

Below are a few examples of things that one could want to describe (click links to download files):

• Attributes of IDHA data model. Mireille has worked on assigning UCDs to the current attributes.
• VOX : VO "experimental" UCD, defined for SIAP
  • Roy Williams suggested some ucd for vox
  • List of VOX elements for input to the assignment tool
  • Example result of the automated assignment
• Andrea did some experiments on extracting FITS keywords from images coming from various surveys:
  • List of keywords (ready for input to assignment tool)
  • Result of the assignment (before filtering)

Common concepts between VOX, IDHA model, FITS and UCDs

I have tried to find similarities between attributes of the IDHA data model and VOX elements, and possibly FITS keywords, and how UCDs could fit into this. Below is a summary. Suggested new UCDs have been indicated by ucd=?? The first line of each paragraph defines the concept that is described by VOX or IDHA.

Number of axes of an "image" ucd=?? data.wcs.naxis
= VOX:Image_Naxes
= IDHA:Geometry:Nb_dimensions
= FITS:NAXIS

Size of an image axis ucd=?? data.wcs.naxisN
= VOX:Image_Naxis (note this is an array of values...)
= IDHA:Geometry:Dimension_tab (note this is an array of values...)
= FITS: NAXIS1, NAXIS2, NAXIS3, ...

Size of a pixel in sky coordinates ucd=?? data.wcs.cdelt
= VOX:Image_Scale (note this is an array of values...)
= IDHA:Observation:PixelSize
= FITS: CDELT1, CDELT2, CDELT3, ...

Format, extension, MIME-type for a file or an image ucd=?? data.file.type
= VOX:Image_Format
= IDHA:Observation:CodingType, Observation:Available_Codings (ARRAY!!), 
   View:Visualisation_Coding, Coding:Type_of_Coding, 
   LinktoPixels:Type_of_File

Identification of the bandpass (filter?) ucd=?? inst.filter,id
= VOX:BandPass_ID
= IDHA:Filter:FilterName

Bandpass reference value (frequency, wavelength, or energy) ** can there be a global ucd ?
= VOX:BandPass_RefValue
= IDHA:Filter:Effective_wavelength (more restrictive, ucd=inst.wavelength.effective)

Upper limit of the bandpass 
= VOX:BandPass_HiLimit
= IDHA:Filter:Maximal_wavelength (more restrictive, ucd=inst.wavelength,max)

Lower limit of the bandpass.
= VOX:BandPass_LoLimit
= IDHA:Filter:Minimal_wavelength (more restrictive, ucd=inst.wavelength,min)

File size (in bytes, kb, Mb) ucd=?? data.file.size
= VOX:Image_FileSize
= IDHA:LinktoPixels:Size_of_File