anchor.diff:  = Fixture Definitions
  +James Elliott <james@deepsymmetry.org>
   :icons: font
  -James Elliott <james@deepsymmetry.org>
   
   // Set up support for relative links on GitHub; add more conditions
   // if you need to support other environments and extensions.
  
positive.code: 
  === Channel Specifications
  
  === Head Specifications
  
  As described above, the `:heads` entry in a fixture definition map is
  
negative.code: 
  |===
  
  === Function Specifications
  
  == Channel Creation Functions
  
  TODO: Finish this page.
  
  * Explain how to create function specifications in all their variations,
  with range helpers, etc., and list naming conventions established so
  