anchor.diff:  | G-5 | free and open source | all required dependencies shall be compliant
                                  to the https://creativecommons.org/licenses/by-sa/4.0/[CC-SA-4 licence].
   | G-6 | available via public repositories, like bintray or jcenter.
  +| G-7 | configurable to check multiple HTML files in a single _run_ and produce a joint report.
  +        (useful for e.g. API documentation with many HTML files referencing each other)
   |===
   
   
  
positive.code: .Required Checks
  |===
  | ID | Check | Description
  |      R-1 | missing image files | Check all image tags if the referenced
                                  image files exist.
                                  See <<MissingImageFilesChecker>>
  | [BrokenCrossReferences] R-2 | broken internal links | Check all internal links from anchor-tags
                                  (href="XYZ") if the link targets "XYZ" are defined.
                                  See <<BrokenCrossReferencesChecker>>
  | [MissingLocalResources] R-3  | missing local files, either other html-files, pdf's or similar.
                                  See <<MissingLocalResourcesChecker>>
  | [DuplicateLinkTargets] R-4 | duplicate link targets | Check all bookmark definitions
                                 (... id="XYZ") wether the id's ("XYZ") are unique.
                                 See <<DuplicateLinkTargetsChecker>>
  | [MissingImgAltAttribute] | missing alt-attribute in image-tags.
                              See <<MissingImgAltAttributeChecker>>
  |===
  
  
  
negative.code: | link-target       | Either a location in the current document (identified by ->id), another document (identified by URI)
                          or another resource to view or download.
  | local resource    | local file, either other html files or other filetypes (e.g. pdf, docx)
  | URI               | Universal Resource Identifier. Defined in http://www.ietf.org/rfc/rfc2396.txt[RFC-2396]
                        The ultimate source of truth concerning link syntax and semantic.
  
  |===
  
  
  