diff --git a/index.html b/index.html
index eb967034d..e87ace79a 100644
--- a/index.html
+++ b/index.html
@@ -436,13 +436,20 @@ <h3>Use Cases and Requirements</h3>
 <!-- requirement list start -->
         <ul>
           <li>
+          <li>
+<a>Credentials</a> represent statements made by an <a>issuer</a>.
+          </li>
 <a>Verifiable credentials</a> represent statements made by an <a>issuer</a> in
 a tamper-evident and privacy-respecting manner.
           </li>
           <li>
-<a>Holders</a> assemble collections of <a>verifiable credentials</a> from
-different <a>issuers</a> into a single artifact, a
-<a>verifiable presentation</a>.
+<a>Holders</a> assemble collections of <a>credentials</a> and/or
+<a>verifiable credentials</a> from different <a>issuers</a> into a single
+artifact, a <a>presentation</a>.
+          </li>
+          <li>
+Holders transform <a>presentations</a> into <a>verifiable presentations</a>
+to render them tamper-evident. 
           </li>
           <li>
 <a>Issuers</a> can issue <a>verifiable credentials</a> about any <a>subject</a>.
@@ -514,6 +521,17 @@ <h3>Use Cases and Requirements</h3>
 <a>Issuers</a> can issue revocable <a>verifiable credentials</a>.
           </li>
           <li>
+The processes of cryptographically protecting <a>credentials</a> and
+<a>presentations</a>, and verifying <a>verifiable credentials</a> and
+<a>verifiable presentations</a>, have to be deterministic, bi-directional, and
+lossless. Any verification of a <a>verifiable credential</a> or
+<a>verifiable presentation</a> has to be transformable to the generic data model
+defined in this document in a deterministic process, such that the resulting
+<a>credential</a> or <a>presentation</a> is semantically and syntactically
+equivalent to the original construct, so that it can be processed in an
+interoperable fashion.
+          </li>
+          <li>
 <a>Verifiable credentials</a> and <a>verifiable presentations</a> have to be
 serializable in one or more machine-readable data formats. The process of
 serialization and/or de-serialization has to be deterministic, bi-directional,