anchor.diff:  Existing external link::
     points to https://github.com/aim42
   
  -=== Background
  +==== Background
   
   Html anchor tags contain href attributes, which denote
   the link-target (where the browser shall jump when the appropriate
  
positive.code: = A Simplistic Asciidoc(tor) Test Document
  
  
  // where are images located?
  :imagesdir: ./images
  
negative.code: Missing image::
  image:nonexisting-image.png[this image deliberately missing]
  
  
  == Local Resources
  The term "Local Resources" refers to non-image files referenced
  from html - most often other html files, stylesheets or JavaScript.
  
  kbd:[htmlSC] currently checks only those local resources which are
  referenced from anchor-tags, like the following:
  
  [source,html]
  ----
  <a href="file.html">File</a>
  ---- 
      
  
  == ImageMaps
  ImageMaps allow parts of an image
  to be used as hyperlinks to arbitrary targets. 
  
  
  ==== A correct ImageMap
  The tricky part is that ImageMaps need two html tags to work:
  
  See the following example for a correct ImageMap (in html source)
  
  [source,html]
  ----
  <img src="image.jpg" usemap="#yourmap"> //<1>
  <map name="yourmap"> //<2>
    <area shape="rect" coords="0,0,1,1" href="#test1"> //<3>
    <area shape="circle" coords="0,1,1" href="#test2">
  </map>
  ----
  
  <1> an image (img-tag) with a "usemap" attribute.
  <2> the actual map, defining a number of click-sensitive
  <3> areas on the image together with the respective link targets.
  
  ==== Dangling Map (Without Reference) 
  
  The following map is not referenced by an image:
  
  TODO: 
  
  ==== Missing Map
  An image references a nonexisting map.
  
  TODO: 
  
  ==== Ambigous Map-Name
  A map-name exists more than once.
  
  TODO: 
  
  ==== Empty Map
  No area-tag defined for map.
  
  TODO: 
  
  ==== Broken Link in ImageMap
  A link (href) within an area-tag is broken
  
  TODO:
  
  //end:html-with-errors[]