ignore columnbreak: https://github.com/metanorma/metanorma-bsi/issues…

lib/isodoc/function/blocks.rb

@@ -205,6 +205,8 @@ def source_parse(node, out)
           end
         end
       end
+
+      def columnbreak_parse(node, out); end
     end
   end
 end

lib/isodoc/function/to_word_html.rb

@@ -252,6 +252,7 @@ def parse(node, out)
           when "variant-title" then variant_title(node, out)
           when "span" then span_parse(node, out)
           when "location" then location_parse(node, out)
+          when "columnbreak" then columnbreak_parse(node, out)
           else error_parse(node, out)
           end
         end

spec/isodoc/blocks_spec.rb

@@ -1872,6 +1872,33 @@
      .convert("test", input, true)))).to be_equivalent_to xmlpp(output)
   end
 
+  it "ignores columnbreak" do
+    input = <<~INPUT
+      <iso-standard xmlns="http://riboseinc.com/isoxml">
+              <preface>
+          <clause type="toc" id="_toc" displayorder="1">
+           <title depth="1">Table of contents</title>
+           <columnbreak/>
+          </clause>
+        <foreword displayorder="2">
+      <passthrough format="doc,rfc">&lt;A&gt;</passthrough>
+      </foreword></preface>
+      </iso-standard>
+    INPUT
+    output = <<~OUTPUT
+      #{HTML_HDR}
+                <br/>
+                <div>
+                  <h1 class='ForewordTitle'>Foreword</h1>
+                </div>
+              </div>
+            </body>
+          </html>
+    OUTPUT
+    expect(xmlpp(strip_guid(IsoDoc::HtmlConvert.new({})
+     .convert("test", input, true)))).to be_equivalent_to xmlpp(output)
+  end
+
   it "processes toc" do
     input = <<~INPUT
           <standard-document xmlns='https://www.metanorma.org/ns/standoc' type='semantic' version='1.10.2'>