Add informative text about raising an exception… (#189)

Add informative text about raising an exception and terminating early if a poison dataset is detected.

Fixes #186.

---------

Co-authored-by: Ted Thibodeau Jr <tthibodeau@openlinksw.com>
Co-authored-by: Jeffrey Yasskin <jyasskin@gmail.com>

spec/index.html

@@ -658,7 +658,9 @@ <h2>Blank Node Identifier Issuer State</h2>
     <h2>Canonicalization Algorithm</h2>
 
     <p>The canonicalization algorithm converts an <a>input dataset</a>
-      into a <a>canonicalized dataset</a>. This algorithm will assign
+      into a <a>canonicalized dataset</a> or raises an error if
+      the input dataset is determined to be overly complex.
+      This algorithm will assign
       deterministic identifiers to any <a>blank nodes</a> in the
       <a>input dataset</a>.</p>
 
@@ -1055,7 +1057,8 @@ <h3>Algorithm</h3>
       <p>The following algorithm will run with a minimal number of iterations in each step
         for typical <a>input datasets</a>.
         In some extreme cases, the algorithm can behave poorly, particularly in <a href="#ca.5">Step 5</a>.
-        Implementations MUST prevent against potential denial-of-service attacks.
+        Implementations MUST defend against potential denial-of-service attacks
+        by raising suitable exceptions and terminating early.
         See <a href="#dataset-poisoning"></a> for further information.</p>
 
       <p class="note">Implementations can consider placing limits on the number of
@@ -3718,6 +3721,16 @@ <h2>Changes since the First Public Working Draft of 24 November 2022</h2>
   </ul>
 </section>
 
+<section class="appendix informative" id="changes-from-cr">
+  <h2>Changes since the Candidate Recommentation Snapshot of 31 October 2023</h2>
+  <ul>
+    <li>
+      Clarified that detecting a poison dataset will result in an exception and early
+      termination of the <a href="#canon-algo-algo">Canonicalization Algorithm</a>.
+    </li>
+  </ul>
+</section>
+
 <section id="ack" class="appendix informative">
   <h2>Acknowledgements</h2>