Console any order input output

doc/guide/author/topics.xml

@@ -3792,7 +3792,7 @@
         <subsection>
             <title>Content and Placement of Consoles</title>
 
-            <p>A <tag>console</tag> is a transcript of an interactive session in a terminal or console at a command-line.  It is a sequence of the following elements, in this order, possibly repeated many times as a group: <tag>input</tag>, and <tag>output</tag>.  The <tag>output</tag> is optional.  The content of these two elements is treated as verbatim text (see <xref ref="overview-verbatim-literal"/>), subject to all the exceptions for exceptional characters (see <xref ref="overview-exceptional-characters"/>).  A <attr>prompt</attr> attribute on the <tag>input</tag> can be supplied to provide a system prompt distinct from the actual commands.  The default prompt is a dollar sign followed by a space.  If it is more convenient <attr>prompt</attr> may be supplied on the <tag>console</tag>, to be used in each enclosed <tag>input</tag>.  If you do not want any prompts at all, just use an empty value for <attr>prompt</attr>. A <attr>continuation</attr> attribute may also be supplied at the <tag>input</tag> or <tag>console</tag>. If present, it will apply to the start of each input line following the first.</p>
+            <p>A <tag>console</tag> is a transcript of an interactive session in a terminal or console at a command-line.  It is a sequence of the following elements, in any order, possibly repeated many times: <tag>input</tag>, and <tag>output</tag>.  The content of these two elements is treated as verbatim text (see <xref ref="overview-verbatim-literal"/>), subject to all the exceptions for exceptional characters (see <xref ref="overview-exceptional-characters"/>).  A <attr>prompt</attr> attribute on the <tag>input</tag> can be supplied to provide a system prompt distinct from the actual commands.  The default prompt is a dollar sign followed by a space.  If it is more convenient <attr>prompt</attr> may be supplied on the <tag>console</tag>, to be used in each enclosed <tag>input</tag>.  If you do not want any prompts at all, just use an empty value for <attr>prompt</attr>. A <attr>continuation</attr> attribute may also be supplied at the <tag>input</tag> or <tag>console</tag>. If present, it will apply to the start of each input line following the first.</p>
 
             <p>A <tag>console</tag> may be wrapped in a <tag>listing</tag>, see <xref ref="topic-listing"/>.  This will behave similar to a <tag>figure</tag>, with the <tag>caption</tag> displayed below, and a number assigned.  So, in particular, if your program is important enough to cross-reference, it is an enclosing <tag>listing</tag> that serves as the target.</p>
         </subsection>

examples/sample-article/sample-article.xml

@@ -11509,6 +11509,16 @@ along with PreTeXt.  If not, see <http://www.gnu.org/licenses/>.
                 </input>
             </console>
 
+            <p>A console may start with output. This is useful if you are showing sample use of a program.</p>
+            <listing>
+                <title>Console session, starting with program output</title>
+                <console>
+                    <output>Enter a number:</output>
+                    <input prompt="">42</input>
+                    <output>You entered 42.</output>
+                </console>
+            </listing>
+
             <p>Notice in the HTML version of the above example that when you highlight all, or a portion, of the listing for a cut-and-paste that the prompts are not included.</p>
 
             <p>Now a test of some listings (and pre-formatted text) in a block that likely has a background color in an HTML version.</p>

schema/pretext.xml

@@ -1317,10 +1317,7 @@
                     attribute continuation {text}?,
                     attribute width {text}?,
                     attribute margins {text}?,
-                    (
-                        ConsoleInput,
-                        ConsoleOutput?
-                    )+
+                    ( ConsoleInput  |  ConsoleOutput  )+
                 }
             ProgramPreamble =
                 element preamble {