Consistently use indefinite article in production definitions

Co-authored-by: Olaf Hartig <[email protected]>

Author: niklasl

spec/index.html

@@ -587,23 +587,23 @@ <h3>RDF Documents and Syntaxes</h3>
       <tr>
         <td>triple</td>
         <td><em>a 3-tuple of</em>
-          <a>subject</a>, <a>predicate</a>, <a>object</a></td>
+          <em>a</em> <a>subject</a>, <em>a</em> <a>predicate</a>, <em>and an</em> <a>object</a></td>
       </tr>
       <tr>
         <td>subject</td>
-        <td><em>either</em> <a>IRI</a>
-          <em>or</em> <a>Blank node</a></td>
+        <td><em>either an</em> <a>IRI</a>
+          <em>or a</em> <a>Blank node</a></td>
       </tr>
       <tr>
         <td>predicate</td>
-        <td><a>IRI</a></td>
+        <td><em>an</em> <a>IRI</a></td>
       </tr>
       <tr>
         <td>object</td>
-        <td><em>either</em> <a>IRI</a>
-          <em>or</em> <a>Blank node</a>
-          <em>or</em> <a>Literal</a>
-          <em>or</em> <a>triple</a></td>
+        <td><em>either an</em> <a>IRI</a>
+          <em>or a</em> <a>Blank node</a>
+          <em>or a</em> <a>Literal</a>
+          <em>or a</em> <a>triple</a></td>
       </tr>
     </table>
     <br>
@@ -615,22 +615,22 @@ <h3>RDF Documents and Syntaxes</h3>
       </tr>
       <tr>
         <td>RDF dataset</td>
-        <td><em>a pair of one</em> <a>default graph</a>,
+        <td><em>a pair of a</em> <a>default graph</a>
           <em>and a set of zero or more</em> <a>named graphs</a></td>
       </tr>
       <tr>
         <td>default graph</td>
-        <td><a>RDF graph</a></td>
+        <td><em>an</em> <a>RDF graph</a></td>
       </tr>
       <tr>
         <td>named graph</td>
         <td><em>a pair of</em>
-          <a>graph name</a>, <a>RDF graph</a></td>
+          <em>a</em> <a>graph name</a> <em>and an</em> <a>RDF graph</a></td>
       </tr>
       <tr>
         <td>graph name</td>
-        <td><em>either</em> <a>IRI</a>
-          <em>or</em> <a>Blank node</a></td>
+        <td><em>either an</em> <a>IRI</a>
+          <em>or a</em> <a>Blank node</a></td>
       </tr>
     </table>
   </section>