Thumbnail (tag)
From SnapMap
thumbnail=<url> is to point to a thumbnail image file for the image.
No hard rules, but consider this as being the default version to show in search results or on any page with lots of images. A maximum of 128x128 pixels is a good rule of thumb. For casual photo browsing by a user agent, src and thumbnail should be all a user agent needs to worry about.
Note that we do not currently define what a 'thumbnail' is. Flickr's square thumbnails are well known. The BBC sometimes uses a heavily cropped version as the thumbnail, perhaps only slightly reduced in magnification from the "normal" size image on the news story's page. Therefore, since thumbnails are often used in place of larger images, we might need to require that thumbnails are simply reduced-size versions of the main image, or else define some other tag that is reliably scaled down from the large image.
Example
src=http://www.timesonline.co.uk/multimedia/archive/00629/winner585_629478a.jpg
