Define the publication date as the approval date

doc/main.html

@@ -234,7 +234,7 @@ <h2>Document Numbering</h2>
     <section id="sec-document-numbering-overview">
       <h3>Document Numbering Overview</h3>
       <p>
-        Document numbers shall be unique and uniform across all Engineering Document types. Versions of documents shall be identified by their year of publication and, optionally, their month of publication, appended with a separating colon (e.g., for document #1020: <code>1020:2009</code> or <code>1020:2009-04</code>, the latter indicating publication in April, 2009). <a href="#figure-example-document-number"></a> shows an example of the document numbering structure.
+        Document numbers shall be unique and uniform across all Engineering Document types. Versions of documents shall be identified by the year and month of their approval date, appended with a separating colon (e.g., for document #1020: <code>1020:2009-04</code> indicating approval in April, 2009). <a href="#figure-example-document-number"></a> shows an example of the document numbering structure. The approval date of a document indicates when it was last approved by its consensus body, e.g., Technical Committee. 
       </p>
       <p>
         The Director of Engineering shall assign document numbers (or root document numbers, in the case of multipart documents). Document numbers may be assigned at the request of the Technology Committee Chair(s) at any time after a Project is approved and shall be assigned before a Final Committee Draft ballot is issued.
@@ -289,14 +289,14 @@ <h3>Parts</h3>
         <h4>General</h4>
         <p>
           Closely related Engineering Documents may be created as Parts. A Part of a document is a separate Engineering Document and shall be shown to be related to other  
-          by using the same root document number plus a suffix of a hyphen and the Part number to distinguish among Parts (e.g. <code>1020-2:2009</code>, indicating document 1020, Part 2).
+          by using the same root document number plus a suffix of a hyphen and the Part number to distinguish among Parts (e.g. <code>1020-2:2009-04</code>, indicating document 1020, Part 2).
         </p>
       </section>
 
       <section id="sec-different-types">
         <h4>Parts of Different Types</h4>
         <p>
-          A multipart set of documents may include Parts of different types of Engineering Documents, including Standards, Recommended Practices, and Engineering Guidelines. Each Part’s number shall include the appropriate document type designation (e.g. <code>RP 2046-2:2009</code>).
+          A multipart set of documents may include Parts of different types of Engineering Documents, including Standards, Recommended Practices, and Engineering Guidelines. Each Part’s number shall include the appropriate document type designation (e.g. <code>RP 2046-2:2009-04</code>).
         </p>
       </section>
 
@@ -342,7 +342,7 @@ <h4>Normative References to Multipart Documents</h4>
       <h3>Elements</h3>
       <p>
         Non-prose Elements of Engineering Documents (see <a href="#sec-formats-elements"></a>) shall be designated using a lower case
-        letter (e.g. <code>1020a:2009</code> and <code>1020b:2009</code>). Media such as DVDs, as well as non-PDF formats, shall be clearly marked, as appropriate. The single prose element shall not receive aletter suffix.
+        letter (e.g. <code>1020a:2009-04</code> and <code>1020b:2009-04</code>). Media such as DVDs, as well as non-PDF formats, shall be clearly marked, as appropriate. The single prose element shall not receive aletter suffix.
       </p>
     </section>