5.13. The photo element

The purpose of the photo element is to link the sighting with the observer's library of photographs.

birdnotes.rnc

photo = element photo
{   attribute cat-no { text },      
    attribute url { xsd:anyURI }?,  
    text?                           
}

	The `cat-no` attribute is required, and specifies the catalog number of the image.
	If there is a rendering of this photo available on the web, use the `url` to specify its Universal Resource Identifier. Optional.
	You can add text content to a `photo` element for remarks on the photo.

A system for encoding bird field notes