diff --git a/src/edit.xsl b/src/edit.xsl
index ae9879a..9954b63 100644
--- a/src/edit.xsl
+++ b/src/edit.xsl
@@ -2338,7 +2338,7 @@ version="3.0">
         <xsl:call-template name="rdfae:disarm-sweep"/>
         <ixsl:set-property name="draggedBlock" select="." object="rdfae:editor-state()"/>
         <ixsl:set-property name="effectAllowed" select="'move'" object="$transfer"/>
-        <xsl:sequence select="ixsl:call($transfer, 'setData', [ 'application/x-rdfa-editor-block', '' ])[current-date() lt xs:date('2000-01-01')]"/>
+        <xsl:sequence select="ixsl:call($transfer, 'setData', [ 'application/vnd.atomgraph.rdfa-editor.block', '' ])[current-date() lt xs:date('2000-01-01')]"/>
         <xsl:sequence select="ixsl:call($transfer, 'setDragImage', [ ., 0, 0 ])[current-date() lt xs:date('2000-01-01')]"/>
         <xsl:sequence select="ixsl:call(ixsl:get(., 'classList'), 'add', [ 'dragging' ])[current-date() lt xs:date('2000-01-01')]"/>
     </xsl:template>
@@ -2364,7 +2364,7 @@ version="3.0">
         <xsl:for-each select="ancestor-or-self::*[rdfae:draggable-block(.)][1]">
             <ixsl:set-property name="draggedBlock" select="." object="rdfae:editor-state()"/>
             <ixsl:set-property name="effectAllowed" select="'move'" object="$transfer"/>
-            <xsl:sequence select="ixsl:call($transfer, 'setData', [ 'application/x-rdfa-editor-block', '' ])[current-date() lt xs:date('2000-01-01')]"/>
+            <xsl:sequence select="ixsl:call($transfer, 'setData', [ 'application/vnd.atomgraph.rdfa-editor.block', '' ])[current-date() lt xs:date('2000-01-01')]"/>
             <xsl:sequence select="ixsl:call($transfer, 'setDragImage', [ ., 0, 0 ])[current-date() lt xs:date('2000-01-01')]"/>
             <xsl:sequence select="ixsl:call(ixsl:get(., 'classList'), 'add', [ 'dragging' ])[current-date() lt xs:date('2000-01-01')]"/>
         </xsl:for-each>
@@ -2375,7 +2375,7 @@ version="3.0">
         <xsl:variable name="dragged" select="ixsl:get(rdfae:editor-state(), 'draggedBlock')"/>
         <xsl:variable name="target" as="element()?" select="rdfae:drop-target-of(., $event)"/>
         <xsl:if test="exists($dragged) and exists($target)
-                and rdfae:has-transfer-type($event, 'application/x-rdfa-editor-block')">
+                and rdfae:has-transfer-type($event, 'application/vnd.atomgraph.rdfa-editor.block')">
             <xsl:sequence select="ixsl:call($event, 'preventDefault', [])[current-date() lt xs:date('2000-01-01')]"/>
             <ixsl:set-property name="dropEffect" select="'move'" object="ixsl:get($event, 'dataTransfer')"/>
             <xsl:call-template name="rdfae:clear-drop-marks"/>
@@ -2393,7 +2393,7 @@ version="3.0">
         <xsl:variable name="dragged" select="ixsl:get(rdfae:editor-state(), 'draggedBlock')"/>
         <xsl:variable name="target" as="element()?" select="rdfae:drop-target-of(., $event)"/>
         <xsl:if test="exists($dragged) and exists($target)
-                and rdfae:has-transfer-type($event, 'application/x-rdfa-editor-block')">
+                and rdfae:has-transfer-type($event, 'application/vnd.atomgraph.rdfa-editor.block')">
             <xsl:sequence select="ixsl:call($event, 'preventDefault', [])[current-date() lt xs:date('2000-01-01')]"/>
             <xsl:call-template name="rdfae:clear-drop-marks"/>
             <!-- transient drag state must not reach the undo snapshot -->
diff --git a/src/navigate.xsl b/src/navigate.xsl
index 90e6ddf..980228b 100644
--- a/src/navigate.xsl
+++ b/src/navigate.xsl
@@ -177,14 +177,14 @@ version="3.0">
         <ixsl:set-property name="draggedSectionHeading"
             select="(ixsl:get(rdfae:editor-state(), 'tocRoot')/(h1 | h2 | h3))[$index]" object="rdfae:editor-state()"/>
         <ixsl:set-property name="effectAllowed" select="'move'" object="$transfer"/>
-        <xsl:sequence select="ixsl:call($transfer, 'setData', [ 'application/x-rdfa-editor-section', '' ])[current-date() lt xs:date('2000-01-01')]"/>
+        <xsl:sequence select="ixsl:call($transfer, 'setData', [ 'application/vnd.atomgraph.rdfa-editor.section', '' ])[current-date() lt xs:date('2000-01-01')]"/>
         <xsl:sequence select="ixsl:call(ixsl:get(., 'classList'), 'add', [ 'dragging' ])[current-date() lt xs:date('2000-01-01')]"/>
     </xsl:template>
 
     <xsl:template match="li[contains-token(@class, 'toc-item')]" mode="ixsl:ondragover">
         <xsl:variable name="event" select="ixsl:event()"/>
         <xsl:if test="exists(ixsl:get(rdfae:editor-state(), 'draggedSectionHeading'))
-                and rdfae:has-transfer-type($event, 'application/x-rdfa-editor-section')">
+                and rdfae:has-transfer-type($event, 'application/vnd.atomgraph.rdfa-editor.section')">
             <xsl:sequence select="ixsl:call($event, 'preventDefault', [])[current-date() lt xs:date('2000-01-01')]"/>
             <ixsl:set-property name="dropEffect" select="'move'" object="ixsl:get($event, 'dataTransfer')"/>
             <xsl:call-template name="rdfae:clear-drop-marks">
@@ -203,7 +203,7 @@ version="3.0">
         <xsl:call-template name="rdfae:clear-drop-marks">
             <xsl:with-param name="scope" select="id('toc-list', ixsl:page())//li"/>
         </xsl:call-template>
-        <xsl:if test="exists($source) and rdfae:has-transfer-type($event, 'application/x-rdfa-editor-section')">
+        <xsl:if test="exists($source) and rdfae:has-transfer-type($event, 'application/vnd.atomgraph.rdfa-editor.section')">
             <xsl:sequence select="ixsl:call($event, 'preventDefault', [])[current-date() lt xs:date('2000-01-01')]"/>
             <!-- bare-variable positional predicate: SaxonJS evaluates computed numeric
                  predicates as booleans in this context -->
diff --git a/tests/browser/editor.mjs b/tests/browser/editor.mjs
index 9a0ee2c..4e6e68d 100644
--- a/tests/browser/editor.mjs
+++ b/tests/browser/editor.mjs
@@ -271,7 +271,7 @@ results.dnd = await page.evaluate(async () => {
     handle.dispatchEvent(new MouseEvent('mousedown', { bubbles: true }));
     const draggableSet = dragged.getAttribute('draggable') === 'true';
     const dt = new DataTransfer();
-    dt.setData('application/x-rdfa-editor-block', '');
+    dt.setData('application/vnd.atomgraph.rdfa-editor.block', '');
     dragged.dispatchEvent(new DragEvent('dragstart', { bubbles: true, dataTransfer: dt }));
     const rect = target.getBoundingClientRect();
     target.dispatchEvent(new DragEvent('dragover', { bubbles: true, cancelable: true, dataTransfer: dt,
diff --git a/tests/browser/features.mjs b/tests/browser/features.mjs
index 8837943..37354aa 100644
--- a/tests/browser/features.mjs
+++ b/tests/browser/features.mjs
@@ -89,7 +89,7 @@ await page.evaluate(() => {
     const target = content.querySelector(':scope > blockquote');
     dragged.querySelector('.drag-handle').dispatchEvent(new MouseEvent('mousedown', { bubbles: true }));
     const dt = new DataTransfer();
-    dt.setData('application/x-rdfa-editor-block', '');
+    dt.setData('application/vnd.atomgraph.rdfa-editor.block', '');
     dragged.dispatchEvent(new DragEvent('dragstart', { bubbles: true, dataTransfer: dt }));
     const rect = target.getBoundingClientRect();
     target.dispatchEvent(new DragEvent('dragover', { bubbles: true, cancelable: true, dataTransfer: dt, clientY: rect.bottom - 2 }));
@@ -164,7 +164,7 @@ await page.evaluate(() => {
     const byLabel = t => items.find(li => li.querySelector(':scope > .toc-label').textContent === t);
     const source = byLabel('Company'), target = byLabel('Publications');
     const dt = new DataTransfer();
-    dt.setData('application/x-rdfa-editor-section', '');
+    dt.setData('application/vnd.atomgraph.rdfa-editor.section', '');
     source.dispatchEvent(new DragEvent('dragstart', { bubbles: true, dataTransfer: dt }));
     const rect = target.getBoundingClientRect();
     target.dispatchEvent(new DragEvent('dragover', { bubbles: true, cancelable: true, dataTransfer: dt, clientY: rect.bottom - 1 }));
@@ -195,7 +195,7 @@ await page.evaluate(() => {
     const byLabel = t => items.find(li => li.querySelector(':scope > .toc-label').textContent === t);
     const source = byLabel('Demo document'), target = byLabel('Queries');
     const dt = new DataTransfer();
-    dt.setData('application/x-rdfa-editor-section', '');
+    dt.setData('application/vnd.atomgraph.rdfa-editor.section', '');
     source.dispatchEvent(new DragEvent('dragstart', { bubbles: true, dataTransfer: dt }));
     const rect = target.getBoundingClientRect();
     target.dispatchEvent(new DragEvent('drop', { bubbles: true, cancelable: true, dataTransfer: dt, clientY: rect.bottom - 1 }));
diff --git a/tests/browser/multiinstance.mjs b/tests/browser/multiinstance.mjs
index a494d1b..973c37b 100644
--- a/tests/browser/multiinstance.mjs
+++ b/tests/browser/multiinstance.mjs
@@ -64,7 +64,7 @@ await page.evaluate(() => {
     const target = document.querySelector('#notes > p');
     block.querySelector('.drag-handle').dispatchEvent(new MouseEvent('mousedown', { bubbles: true }));
     const dt = new DataTransfer();
-    dt.setData('application/x-rdfa-editor-block', '');
+    dt.setData('application/vnd.atomgraph.rdfa-editor.block', '');
     block.dispatchEvent(new DragEvent('dragstart', { bubbles: true, dataTransfer: dt }));
     const rect = target.getBoundingClientRect();
     for (const type of ['dragover', 'drop']) {
diff --git a/tests/browser/tables.mjs b/tests/browser/tables.mjs
index ea0bce2..c654b57 100644
--- a/tests/browser/tables.mjs
+++ b/tests/browser/tables.mjs
@@ -300,7 +300,7 @@ results.drag = await page.evaluate(() => {
     dragged.querySelector('.drag-handle').dispatchEvent(new MouseEvent('mousedown', { bubbles: true }));
     const draggableSet = dragged.getAttribute('draggable') === 'true';
     const dt = new DataTransfer();
-    dt.setData('application/x-rdfa-editor-block', '');
+    dt.setData('application/vnd.atomgraph.rdfa-editor.block', '');
     dragged.dispatchEvent(new DragEvent('dragstart', { bubbles: true, dataTransfer: dt }));
     const rect = target.getBoundingClientRect();
     target.dispatchEvent(new DragEvent('dragover', { bubbles: true, cancelable: true, dataTransfer: dt, clientY: rect.bottom - 2 }));