metadata - Which IPTC title fields to use?

I decided to set the titles of my photos in Lightroom (via the IPTC metadata) instead of my web-based gallery software. However, I'm somewhat unsure about the proper usage of the various title-ish fields: Headline, Caption, Title

For example, I have a photo showing a head banger on a concert and when publishing the photo I'm going to show "no concert without headbanging" below the photo.

Obviously I could put this in each of those fields and simply let my gallery software use whatever field is present (and use only one of them). However, that would be somewhat dirty and most likely not the way those fields are meant to be used.

Answer

The IPTC Metadata Standard supplies that information, but in short:

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  Headline - A brief synopsis of the caption. It's not the same as title.

  
  


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  Title - A shorthand reference for the item. A human readable name which can be text or numeric, may be the file name, but doesn't have to be. It is not the same as headline.

  
  



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  Caption - Is Description (as of 1.1), which is basically the description, including caption, of the items content.

  
  

Read through the standard, you'll probably find it interesting. Bear in mind, it is intended for use by the International Press and it's geared that way. By the way, from the above, the way I read the standard is that you should be using Description (Caption) for example you gave above. Corrected: Services like Facebook or Flicker will use title or filename if supplied (thanks Bart).