anchor.diff:  %% the tuple returned for that data point shall be `{ DP, {error, undefined}'.
   %%
   %% For example, if the provided `DataPoint' argument is set to `[ min,
  -%% max, xyzzy ]', and only `min' and `max' are data points supported
  +%% max, xyzzy ]', and only `min' and `max' are supported
   %% by the probe, the returned list shall look like below:
   %%
   %% <pre lang="erlang">
   %%      [{ min, 0.1265 }, { max, 3338.21 }, { xyzzy, { error, unsupported } ]</pre>
   %%
  -%% The `probe_get_value/2' implementation shall return `{ok, List}', where
  -%% `List' is the list of data points described above. No new state is returned
  -%% by this function.
  +%% The `probe_get_value/2' implementation shall return `{ok, List}',
  +%% where `List' is the list of data points and their values described
  +%% above. No new state is returned by this function.
  +%%
  +%% 
  +%% === probe_get_datapoints/1 ===
  +%% The `probe_get_datapoints/1' function is invoked as follows:
  +%% 
  +%% <pre lang="erlang">
  +%%      probe_get_datapoints(State)</pre>
  +%% 
  +%% The `probe_get_datapoints/1' shall return a list with all data points
  +%% supported by the probe
  +%%
  +%% The arguments are as follows:
  +%%
  +%% + `State'
  +%%     The probe state, originally returned by `probe_init/3' and subsequentially
  +%%     modified by other probe implementation calls.
  +%% 
  +%% The `probe_get_datapoints/1' implementation is invoked by
  +%% `exometer:info/2', which calls `exometer_probe:get_datapoints/3',
  +%% which invokes the probe implementation.
  +%% 
  +%% In cases where `exometer:get_value/2' is called with `default' as a
  +%% single data point, `probe_get_datapoints/1' is also called to
  +%% retrieve a list of all supported data points, which is then
  +%% forwarded to `probe_get_value/2'.
  +%% 
  +%% The implementation of `probe_get_datapoints/1' shall return `{ok, DpList}',
  +%% where `DpList' is a list of data point atoms supported by the probe.
  +%%
  +%%
  +%% === probe_reset/1 ===
  +%% The `probe_reset/1' function is invoked as follows:
  +%% 
  +%% <pre lang="erlang">
  +%%      probe_reset(State)</pre>
  +%% 
  +%% The `probe_reset/1' shall reset the state of the probe to its initial state.
  +%%
  +%% The arguments are as follows:
  +%%
  +%% + `State'
  +%%     The probe state, originally returned by `probe_init/3' and subsequentially
  +%%     modified by other probe implementation calls.
  +%% 
  +%% 
  +%% The `probe_reset/1' implementation is invoked by
  +%% `exometer:reset/1', which calls `exometer_probe:reset/3', which
  +%% invokes the probe implementation.
  +%% 
  +%% The implementation of `probe_reset/1' shall return `{ok,
  +%% NewState}', where `NewState' contains the reset state of the probe.
  +%%
  +%%
  +%% === probe_sample/1 ===
  +%% The `probe_sample/1' function is invoked as follows:
  +%% 
  +%% <pre lang="erlang">
  +%%      probe_sample(State)</pre>
  +%% 
  +%% The `probe_sample/1' implementation shall sample data from the
  +%% subsystem the probe is integrated with.
  +%%
  +%% The arguments are as follows:
  +%%
  +%% + `State'
  +%%     The probe state, originally returned by `probe_init/3' and subsequentially
  +%%     modified by other probe implementation calls.
  +%% 
  +%% When invoked, `probe_sample/1' is expected to interface the
  +%% sub-system (/proc, /sysfs, etc) monitored by the probe, extract the
  +%% relevant data from it, and return an updated probe state that
  +%% incorporates the extracted data.
  +%%
  +%% The `probe_sample/1' function is invoked by the probe thread at
  +%% intervals specified by the `{sample_interval, Intv}' option
  +%% provided to `exometer_probe:new/3'. If this option is missing, or
  +%% set to infinity, `probe_sample/1' will never be called.
  +%%
  +%% The implementation of `probe_sample/1' shall return `{ok,
  +%% NewState}', where `NewState' contains the new state of the probe
  +%% with the sampled data integrated into it.
  +%%
  +%%
  +%% === probe_handle_msg/2 ===
  +%% The `probe_handle_msg/2' function is invoked as follows:
  +%% 
  +%% <pre lang="erlang">
  +%%      probe_handle_msg(Msg, State)</pre>
  +%% 
  +%% The `probe_handle_msg/1' is invoked to process messages received
  +%% by the probe process.
  +%%
  +%% The arguments are as follows:
  +%%
  +%% + `State'
  +%%     The probe state, originally returned by `probe_init/3' and subsequentially
  +%%     modified by other probe implementation calls.
  +%% 
  +%% + `Msg'
  +%%     The probe state, originally returned by `probe_init/3' and subsequentially
  +%%     modified by other probe implementation calls.
  +%% 
  +%% The implementation of this function will be called by the probe's
  +%% process when it receives a message that is not recognized by the
  +%% internal receive loop.
  +%%
  +%% The implementation of `probe_handle_msg/2' shall return `{ok,
  +%% NewState}', where `NewState' contains the new state of the probe
  +%% that reflects the processed message.
   %%
   
   -module(exometer_probe).
  
positive.code: %% The arguments are as follows:
  %%
  %% + `State'
  %%     <br/>The probe state, originally returned by `probe_init/3' and subsequentially
  %%     modified by other probe implementation calls.
  %%
  %%
  %% === probe_setopts/2 ===
  
negative.code: %% <pre lang="erlang">
  %%      probe_setopts(Opts, State)</pre>
  %% 
  %% The `probe_setopts/2' implementation is invoked by `exometer:setopts/2', which
  %% calls `exometer_probe:setopts/4', which invokes the probe
  %% implementation.
  %%
  %% The implementation of this function shall modify the options of a
  %% probe. The `setopts/4' function, which will process standard
  %% options before invoking `probe_setopts/2' with the remaining
  %% options. See the documentation for `probe_init/3' for details.
  %%
  %% The arguments are as follows:
  %%
  %% + `Opts'
  %%     The probe-specific options to be processed.
  %% 
  %% + `State'
  %%     The probe state, originally returned by `probe_init/3' and subsequentially
  %%     modified by other probe implementation calls.
  %% 
  %% This function shall return `{ok, NewState}' where `NewState' is
  %% the modified probe state that incorporates the new options.
  %% 
  %%
  %% === probe_update/2 ===
  %% The `probe_update/2' function is invoked as follows:
  %% 
  