anchor.diff:          %% block any operation that writes, modifies or deletes data on the
           %% storage. Such storage can only be used to import data into the space.
           %% Mandatory to ensure proper behaviour if the backend storage is
  -        %% actually configured as readonly.
  +        %% actually configured as readonly. This option is available only for
  +        %% imported storages.
           readonly => {boolean, optional},
           %% Type of the modified storage. Must be given explicitly and must match
           %% the actual type of subject storage - this redundancy is needed due to
  
positive.code:         %% block any operation that writes, modifies or deletes data on the
          %% storage. Such storage can only be used to import data into the space.
          %% Mandatory to ensure proper behaviour if the backend storage is
          %% actually configured as readonly.
          readonly => {boolean, optional},
          %% Desired number of object replicas in the pool. When below this number
          %% the pool still may be used in 'degraded' mode. Defaults to
  
negative.code:         %% block any operation that writes, modifies or deletes data on the
          %% storage. Such storage can only be used to import data into the space.
          %% Mandatory to ensure proper behaviour if the backend storage is
          %% actually configured as readonly. This option is available only for
          %% imported storages.
          readonly => {boolean, optional},
          %% Minimum latency in milliseconds, which should be simulated for
          %% selected operations.
  