Update website

1 files changed, 64 insertions, 18 deletions

diff --git a/manual/index.html b/manual/index.html
index 1ecf4db3..2763e3a2 100644
--- a/manual/index.html
+++ b/manual/index.html
@@ -387,23 +387,41 @@ using some command-line options:</p>
                     Identity: <code>.</code>
                     
                   </h3>
-                  <p>The absolute simplest filter is <code>.</code> .  This is a filter that
-takes its input and produces it unchanged as output.  That is,
-this is the identity operator.</p>
-<p>Since jq by default pretty-prints all output, this trivial
-program can be a useful way of formatting JSON output from,
-say, <code>curl</code>.</p>
-<p>An important point about the identity filter is that it
-guarantees to preserve the literal decimal representation
-of values. This is particularly important when dealing with numbers
-which can't be losslessly converted to an IEEE754 double precision
+                  <p>The absolute simplest filter is <code>.</code> .  This filter takes its
+input and produces the same value as output.  That is, this
+is the identity operator.</p>
+<p>Since jq by default pretty-prints all output, a trivial
+program consisting of nothing but <code>.</code> can be used to format
+JSON output from, say, <code>curl</code>.</p>
+<p>Although the identity filter never modifies the value of its
+input, jq processing can sometimes make it appear as though
+it does.  For example, using the current implementation of
+jq, we would see that the expression:</p>
+<pre><code>`1E1234567890 | .`
+</code></pre>
+<p>produces <code>1.7976931348623157e+308</code> on at least one platform.
+This is because, in the process of parsing the number, this
+particular version of jq has converted it to an IEEE754
+double-precision representation, losing precision.</p>
+<p>The way in which jq handles numbers has changed over time
+and further changes are likely within the parameters set by
+the relevant JSON standards.  The following remarks are
+therefore offered with the understanding that they are
+intended to be descriptive of the current version of jq and
+should not be interpreted as being prescriptive:</p>
+<p>(1) Any arithmetic operation on a number that has not
+already been converted to an IEEE754 double precision
+representation will trigger a conversion to the IEEE754
 representation.</p>
-<p>jq doesn't truncate the literal numbers to double unless there
-is a need to make arithmetic operations with the number.
-Comparisons are carried out over the untruncated big decimal
-representation of the number.</p>
-<p>jq will also try to maintain the original decimal precision of the provided
-number literal. See below for examples.</p>
+<p>(2) jq will attempt to maintain the original decimal
+precision of number literals, but in expressions such
+<code>1E1234567890</code>, precision will be lost if the exponent is
+too large.</p>
+<p>(3) In jq programs, a leading minus sign will trigger the
+conversion of the number to an IEEE754 representation.</p>
+<p>(4) Comparisons are carried out using the untruncated
+big decimal representation of numbers if available, as
+illustrated in one of the following examples.</p>
 
                   
                     <div>
@@ -429,7 +447,21 @@ number literal. See below for examples.</p>
                           </table>
                         
                           <table>
-                            <tr><th></th><td class="jqprogram">jq '. | tojson'</td></tr>
+                            <tr><th></th><td class="jqprogram">jq '.'</td></tr>
+                            <tr><th>Input</th><td>0.12345678901234567890123456789</td></tr>
+                            
+                            
+                              <tr>
+                                
+                                  <th>Output</th>
+                                
+                                <td>0.12345678901234567890123456789</td>
+                              </tr>
+                            
+                          </table>
+                        
+                          <table>
+                            <tr><th></th><td class="jqprogram">jq '[., tojson]'</td></tr>
                             <tr><th>Input</th><td>12345678909876543212345</td></tr>
                             
                             
@@ -437,7 +469,21 @@ number literal. See below for examples.</p>
                                 
                                   <th>Output</th>
                                 
-                                <td>&#34;12345678909876543212345&#34;</td>
+                                <td>[12345678909876543212345,&#34;12345678909876543212345&#34;]</td>
+                              </tr>
+                            
+                          </table>
+                        
+                          <table>
+                            <tr><th></th><td class="jqprogram">jq '. &lt; 0.12345678901234567890123456788'</td></tr>
+                            <tr><th>Input</th><td>0.12345678901234567890123456789</td></tr>
+                            
+                            
+                              <tr>
+                                
+                                  <th>Output</th>
+                                
+                                <td>false</td>
                               </tr>
                             
                           </table>