anchor.diff:  %% a function declaration so breaks all of our behavior callbacks.
   -include_lib("webmachine/include/wm_reqdata.hrl").
   -include_lib("mixer/include/mixer.hrl").
  +-include("heimdall.hrl").
   
   -type permission() :: create | read | update | delete | grant.
  --type entity_type() :: actor | group | container | object.
   
   %% Share resource state shared by all heimdall resource modules
   %%
  
positive.code: 
            %% What member type are we checking for?  This will always be an actor or
            %% a group
            member_type :: entity_type(),
  
            %% What's the ID of the member
            member_id :: binary(),
  
            %% Who's asking?
            requestor_id :: binary(),
  
            %% Which module is handling this request?
            module :: atom()
  
negative.code: 
            %% Who are we working with?  This is the object in question, i.e., for
            %% /<type>/<id> this is <id>
            authz_id :: auth_id(),
  
            %% What kind of resource are we talking about here?
            request_type :: auth_type(),
  
            %% What is the ACL on the resource?
            acl :: term(),
  