knowledgepixels · ashleycaselli · Sep 15, 2026
diff --git a/src/main/java/com/knowledgepixels/nanodash/component/SourceNanopub.html b/src/main/java/com/knowledgepixels/nanodash/component/SourceNanopub.html
@@ -3,7 +3,7 @@
 
 <body>
   <wicket:panel>
-    <a wicket:id="np" class="source" rel="cite-as" vocab="https://www.w3.org/ns/iana/link-relations/relation#">^</a>
+    <a wicket:id="np" class="source">^</a>
   </wicket:panel>
 </body>
 

diff --git a/src/main/java/com/knowledgepixels/nanodash/page/ExplorePage.java b/src/main/java/com/knowledgepixels/nanodash/page/ExplorePage.java
@@ -94,8 +94,21 @@ public String getMountPath() {
         return MOUNT_PATH;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    protected String getCiteAsIri() {
+        return citeAsIri;
+    }
+
     private Nanopub publishedNanopub = null;
 
+    // Set when the explored id resolves to a nanopublication, i.e. when this is that
+    // nanopublication's own page. Only then does the page announce what to cite it as; a page
+    // about a term that merely mentions nanopublications announces nothing (issue #716).
+    private String citeAsIri = null;
+
     /**
      * Constructor for ExplorePage.
      *
@@ -196,6 +209,7 @@ private void initPage() {
         boolean isNanopubId = (np != null);
         if (isNanopubId) {
             tempRef = np.getUri().stringValue();
+            citeAsIri = tempRef;
         }
         if (!isNanopubId && tempRef.matches("^(.*[^A-Za-z0-9-_])?RA[A-Za-z0-9-_]{43}[^A-Za-z0-9-_].*$")) {
             np = Utils.getAsNanopub(tempRef.replaceFirst("^(.*[^A-Za-z0-9-_])?(RA[A-Za-z0-9-_]{43})[^A-Za-z0-9-_].*$", "$2"));

diff --git a/src/main/java/com/knowledgepixels/nanodash/page/NanodashPage.java b/src/main/java/com/knowledgepixels/nanodash/page/NanodashPage.java
@@ -372,6 +372,20 @@ protected RdfSource getRdfSource() {
         return null;
     }
 
+    /**
+     * The IRI this page should be cited as, or null where it should not be cited as anything.
+     * <p>
+     * A page returns one only when it <em>is</em> that resource's own page -- the one its IRI
+     * resolves to. A page that merely links to a nanopublication is not announcing itself as
+     * that nanopublication, and a listing that links to many is announcing itself as none of
+     * them (issue #716).
+     *
+     * @return the IRI to be cited as, or null
+     */
+    protected String getCiteAsIri() {
+        return null;
+    }
+
     /**
      * Answers a client that asked for RDF in its {@code Accept} header with a 303 to the
      * download page in the matching format, and lets everyone else have the HTML (issue
@@ -420,6 +434,31 @@ private void renderRdfLinks(IHeaderResponse response) {
         response.render(StringHeaderItem.forString("<script type=\"application/ld+json\">\n" + jsonLd + "\n</script>\n"));
     }
 
+    // The vocabulary the cite-as relation is a term of, scoped to the one link that uses it:
+    // with it in scope every token of that link's rel resolves against it, which is why the
+    // link carries the relation and nothing else (issues #633, #716).
+    private static final String LINK_RELATIONS_VOCAB = "https://www.w3.org/ns/iana/link-relations/relation#";
+
+    /**
+     * Renders the {@code cite-as} link (<a href="https://datatracker.ietf.org/doc/html/rfc8574">RFC
+     * 8574</a>) that says which IRI this page is to be cited as, for pages that are a resource's
+     * own page. Annotation tools read it to anchor to the resource rather than to whichever URL
+     * the reader arrived by (issue #633).
+     * <p>
+     * The {@code vocab} attribute lets an RDFa parser resolve the relation, as dokieli's does.
+     * Rendered into the head rather than onto the visible IRI link: a {@code rel} is a list of
+     * tokens and the visible link already carries {@code noopener noreferrer}, which the vocab
+     * would turn into link-relation triples of their own.
+     *
+     * @param response the header response to render into
+     */
+    private void renderCiteAs(IHeaderResponse response) {
+        String citeAsIri = getCiteAsIri();
+        if (citeAsIri == null || citeAsIri.isBlank()) return;
+        response.render(MetaDataHeaderItem.forLinkTag("cite-as", citeAsIri)
+                .addTagAttribute("vocab", LINK_RELATIONS_VOCAB));
+    }
+
     /**
      * Renders the description, canonical URL, Open Graph and Twitter card tags that
      * search engines and link previews read (issue #704).
@@ -470,6 +509,7 @@ public void renderHead(IHeaderResponse response) {
         super.renderHead(response);
         renderPageMetadata(response);
         renderRdfLinks(response);
+        renderCiteAs(response);
         response.render(CssHeaderItem.forUrl(getStyleSheetUrl()));
         response.render(JavaScriptHeaderItem.forReference(getApplication().getJavaScriptLibrarySettings().getJQueryReference()));
         response.render(JavaScriptReferenceHeaderItem.forReference(nanodashJs));

diff --git a/src/test/java/com/knowledgepixels/nanodash/page/CiteAsLinkTest.java b/src/test/java/com/knowledgepixels/nanodash/page/CiteAsLinkTest.java
@@ -0,0 +1,76 @@
+package com.knowledgepixels.nanodash.page;
+
+import com.knowledgepixels.nanodash.WicketApplication;
+import org.apache.wicket.util.tester.WicketTester;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * The {@code cite-as} link of RFC 8574 says which IRI the page being read is to be cited as,
+ * so it belongs on a resource's own page and nowhere else: a page that merely links to
+ * nanopublications is not announcing itself as one of them (issues #633, #716).
+ */
+class CiteAsLinkTest {
+
+    private WicketTester tester;
+
+    @BeforeEach
+    void setUp() {
+        tester = new WicketTester(new WicketApplication());
+    }
+
+    private String render(Class<? extends NanodashPage> pageClass) {
+        tester.startPage(pageClass);
+        return tester.getLastResponse().getDocument();
+    }
+
+    @Test
+    void aResourcesOwnPageSaysWhatToCiteItAs() {
+        String document = render(CiteAsSubjectPage.class);
+        assertTrue(document.contains("rel=\"cite-as\""), document);
+        assertTrue(document.contains("href=\"" + CiteAsSubjectPage.SUBJECT_IRI + "\""), document);
+    }
+
+    // Without the vocabulary in scope an RDFa parser has no IRI to resolve the relation to,
+    // and dokieli -- the reason the link is here at all -- reads it through one.
+    @Test
+    void theRelationIsResolvableByAnRdfaParser() {
+        String document = render(CiteAsSubjectPage.class);
+        assertTrue(document.contains("vocab=\"https://www.w3.org/ns/iana/link-relations/relation#\""), document);
+    }
+
+    // The link carries the relation and nothing else. Every token of a rel resolves against
+    // the vocabulary in scope, so a noopener alongside it would assert a link relation of its
+    // own about the page -- which is why this is a link of its own rather than an attribute on
+    // the visible IRI link, where noopener and noreferrer already sit.
+    @Test
+    void theCiteAsLinkCarriesNoOtherRelation() {
+        String document = render(CiteAsSubjectPage.class);
+        int relIndex = document.indexOf("rel=\"cite-as\"");
+        assertTrue(relIndex > -1, document);
+        int lineStart = document.lastIndexOf("<", relIndex);
+        int lineEnd = document.indexOf(">", relIndex);
+        String tag = document.substring(lineStart, lineEnd + 1);
+        assertFalse(tag.contains("noopener"), tag);
+        assertFalse(tag.contains("noreferrer"), tag);
+    }
+
+    // A page with no subject of its own claims nothing, which is the case every listing and
+    // every page that merely links to a nanopublication falls into.
+    @Test
+    void aPageThatIsNotAResourcesOwnPageClaimsNothing() {
+        String document = render(ErrorPage.class);
+        assertFalse(document.contains("cite-as"), document);
+    }
+
+    @Test
+    void exactlyOneCiteAsIsClaimed() {
+        String document = render(CiteAsSubjectPage.class);
+        assertEquals(1, document.split("rel=\"cite-as\"", -1).length - 1, document);
+    }
+
+}
diff --git a/src/test/java/com/knowledgepixels/nanodash/page/CiteAsSubjectPage.html b/src/test/java/com/knowledgepixels/nanodash/page/CiteAsSubjectPage.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html xmlns:wicket="http://wicket.apache.org">
+<head>
+  <wicket:head>
+    <title wicket:id="pagetitle">Cite-as | nanodash</title>
+  </wicket:head>
+</head>
+<body>
+<wicket:extend>
+  <div class="row-section"><div class="col-12"><p>cite-as test page</p></div></div>
+</wicket:extend>
+</body>
+</html>
diff --git a/src/test/java/com/knowledgepixels/nanodash/page/CiteAsSubjectPage.java b/src/test/java/com/knowledgepixels/nanodash/page/CiteAsSubjectPage.java
@@ -0,0 +1,46 @@
+package com.knowledgepixels.nanodash.page;
+
+import com.knowledgepixels.nanodash.component.TitleBar;
+import org.apache.wicket.markup.html.basic.Label;
+import org.apache.wicket.markup.html.panel.EmptyPanel;
+import org.apache.wicket.request.mapper.parameter.PageParameters;
+
+/**
+ * A stand-in for a page that is a resource's own page, used to render the {@code cite-as}
+ * link without reaching for a nanopublication over the network.
+ */
+public class CiteAsSubjectPage extends NanodashPage {
+
+    /** The IRI this page claims to be cited as. */
+    public static final String SUBJECT_IRI = "https://w3id.org/np/RAAbCdEfGhIjKlMnOpQrStUvWxYz0123456789-_AbCdE";
+
+    /**
+     * @param parameters the page parameters, unused
+     */
+    public CiteAsSubjectPage(final PageParameters parameters) {
+        super(parameters);
+        try {
+            add(new TitleBar("titlebar", this));
+        } catch (Exception ex) {
+            add(new EmptyPanel("titlebar"));
+        }
+        add(new Label("pagetitle", "Cite-as | nanodash"));
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getMountPath() {
+        return "/cite-as-subject";
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    protected String getCiteAsIri() {
+        return SUBJECT_IRI;
+    }
+
+}