diff --git a/waltz-data/src/main/java/org/finos/waltz/data/datatype_decorator/LogicalFlowDecoratorDao.java b/waltz-data/src/main/java/org/finos/waltz/data/datatype_decorator/LogicalFlowDecoratorDao.java
index a27aa818c0..329ecb34de 100644
--- a/waltz-data/src/main/java/org/finos/waltz/data/datatype_decorator/LogicalFlowDecoratorDao.java
+++ b/waltz-data/src/main/java/org/finos/waltz/data/datatype_decorator/LogicalFlowDecoratorDao.java
@@ -305,6 +305,8 @@ public List<DataTypeUsageCharacteristics> findDatatypeUsageCharacteristics(Entit
                 .select(
                         LOGICAL_FLOW_DECORATOR.DECORATOR_ENTITY_ID,
                         LOGICAL_FLOW_DECORATOR.IS_READONLY,
+                        LOGICAL_FLOW_DECORATOR.LAST_UPDATED_BY,
+                        LOGICAL_FLOW_DECORATOR.PROVENANCE,
                         numberOfFlowsSharingDatatype)
                 .from(LOGICAL_FLOW)
                 .innerJoin(LOGICAL_FLOW_DECORATOR).on(LOGICAL_FLOW.ID.eq(LOGICAL_FLOW_DECORATOR.LOGICAL_FLOW_ID)
@@ -315,22 +317,58 @@ public List<DataTypeUsageCharacteristics> findDatatypeUsageCharacteristics(Entit
                 .leftJoin(PHYSICAL_SPEC_DATA_TYPE).on(PHYSICAL_FLOW.SPECIFICATION_ID.eq(PHYSICAL_SPEC_DATA_TYPE.SPECIFICATION_ID)
                         .and(PHYSICAL_SPEC_DATA_TYPE.DATA_TYPE_ID.eq(LOGICAL_FLOW_DECORATOR.DECORATOR_ENTITY_ID)))
                 .where(LOGICAL_FLOW.ID.eq(ref.id()))
-                .groupBy(LOGICAL_FLOW_DECORATOR.DECORATOR_ENTITY_ID, LOGICAL_FLOW_DECORATOR.IS_READONLY)
+                .groupBy(LOGICAL_FLOW_DECORATOR.DECORATOR_ENTITY_ID, LOGICAL_FLOW_DECORATOR.IS_READONLY, LOGICAL_FLOW_DECORATOR.LAST_UPDATED_BY, LOGICAL_FLOW_DECORATOR.PROVENANCE)
                 .fetch(r -> {
                     int usageCount = r.get(numberOfFlowsSharingDatatype);
+                    boolean noUsages = usageCount == 0;
+                    boolean isReadOnly = r.get(LOGICAL_FLOW_DECORATOR.IS_READONLY);
+                    String provenance = r.get(LOGICAL_FLOW_DECORATOR.PROVENANCE);
+                    String lastUpdatedBy = r.get(LOGICAL_FLOW_DECORATOR.LAST_UPDATED_BY);
                     return ImmutableDataTypeUsageCharacteristics.builder()
                             .dataTypeId(r.get(LOGICAL_FLOW_DECORATOR.DECORATOR_ENTITY_ID))
-                            .warningMessageForViewers(usageCount == 0
-                                    ? "Warning: None of the underlying physical flows reference this data type."
-                                    : null)
-                            .warningMessageForEditors(usageCount > 0
-                                    ? format("Cannot be removed as used in %d physical flows. These must be removed first.", usageCount)
-                                    : null)
-                            .isRemovable(usageCount == 0)
+                            .warningMessageForViewers(mkViewerWarningMessage(noUsages, isReadOnly, lastUpdatedBy, provenance))
+                            .warningMessageForEditors(mkEditorWarningMessage(usageCount, isReadOnly, lastUpdatedBy, provenance))
+                            .isRemovable(noUsages && !isReadOnly)
                             .build();
                 });
     }
 
+    private String mkEditorWarningMessage(int usageCount,
+                                          boolean isReadOnly,
+                                          String lastUpdatedBy,
+                                          String provenance) {
+
+        StringBuilder buff = new StringBuilder();
+        if (usageCount > 0 || isReadOnly) {
+            buff.append("Warning:\n");
+        }
+        if (usageCount > 0) {
+            buff.append(format("- Cannot be removed as used in %d physical flows. The data type mappings on these must be removed first\n", usageCount));
+        }
+        if (isReadOnly) {
+            buff.append(format("- Marked as readonly - <span title='last edited by / provenance' class='text-muted'>%s / %s</span>\n", lastUpdatedBy, provenance));
+        }
+        return buff.toString();
+    }
+
+
+    private String mkViewerWarningMessage(boolean noUsages,
+                                          boolean isReadOnly,
+                                          String lastUpdatedBy,
+                                          String provenance) {
+        StringBuilder buff = new StringBuilder();
+        if (noUsages || isReadOnly) {
+            buff.append("Warning:\n");
+        }
+        if (noUsages) {
+            buff.append("- None of the underlying physical flows reference this data type\n");
+        }
+        if (isReadOnly) {
+            buff.append(format("- Marked as readonly - <span title='last edited by / provenance' class='text-muted'>%s / %s</span>\n", lastUpdatedBy, provenance));
+        }
+        return buff.toString();
+    }
+
 
     public int updateRatingsByCondition(AuthoritativenessRatingValue rating, Condition condition) {
         return dsl
diff --git a/waltz-ng/client/common/svelte/DataTypeNodeTooltipContent.svelte b/waltz-ng/client/common/svelte/DataTypeNodeTooltipContent.svelte
index b72059d80b..9709c5ecc1 100644
--- a/waltz-ng/client/common/svelte/DataTypeNodeTooltipContent.svelte
+++ b/waltz-ng/client/common/svelte/DataTypeNodeTooltipContent.svelte
@@ -108,7 +108,7 @@
                       style="vertical-align: middle"
                       size="xl"/>
             </span>
-            {usageCharacteristics.warningMessageForEditors}
+            <Markdown inline={true} text={usageCharacteristics.warningMessageForEditors}/>
         </div>
     </div>
 {/if}
@@ -120,7 +120,7 @@
                       style="vertical-align: middle"
                       size="xl"/>
             </span>
-            {usageCharacteristics.warningMessageForViewers}
+            <Markdown inline={true} text={usageCharacteristics.warningMessageForViewers}/>
         </div>
     </div>
 {/if}
diff --git a/waltz-ng/client/common/svelte/DataTypeTreeNode.svelte b/waltz-ng/client/common/svelte/DataTypeTreeNode.svelte
index 6804a1467e..66ec3c1cad 100644
--- a/waltz-ng/client/common/svelte/DataTypeTreeNode.svelte
+++ b/waltz-ng/client/common/svelte/DataTypeTreeNode.svelte
@@ -38,12 +38,16 @@
     function calcDisabled(filterFn, n) {
         const isUnchecked = filterFn(n);
 
-        return isUnchecked // should be allowed to deselect non-concrete
+        const cannotCheck = isUnchecked // should be allowed to deselect non-concrete
             && ((!nonConcreteSelectable && !n.concrete) || n.unknown);
+
+        const cannotUncheck = ! _.get(n, ["usageCharacteristics", "isRemovable"], true);
+
+        return cannotCheck || cannotUncheck;
     }
 
     function mkTooltipProps(node) {
-        return node;
+        return Object.assign({}, node, {isEditMode: multiSelect});
     }
 
 </script>
@@ -82,6 +86,7 @@
                 {/if}
                     {#if node.usageCharacteristics}
                     <UsageCharacteristicsDecorator usageCharacteristics={node.usageCharacteristics}
+                                                   isEditMode={multiSelect}
                                                    isConcrete={node.concrete}/>
                 {/if}
             </span>
@@ -138,6 +143,7 @@
                                 {/if}
                                 {#if childNode.usageCharacteristics}
                                     <UsageCharacteristicsDecorator usageCharacteristics={childNode.usageCharacteristics}
+                                                                   isEditMode={multiSelect}
                                                                    isConcrete={childNode.concrete}/>
                                 {/if}
                             </div>
@@ -185,5 +191,4 @@
         margin-left: 0;
     }
 
-
 </style>
\ No newline at end of file
diff --git a/waltz-ng/client/common/svelte/UsageCharacteristicsDecorator.svelte b/waltz-ng/client/common/svelte/UsageCharacteristicsDecorator.svelte
index b4ff108c05..913b5db23c 100644
--- a/waltz-ng/client/common/svelte/UsageCharacteristicsDecorator.svelte
+++ b/waltz-ng/client/common/svelte/UsageCharacteristicsDecorator.svelte
@@ -7,24 +7,42 @@
     export let isConcrete;
     export let isEditMode = false;
 
-</script>
 
+    $: isEditable = usageCharacteristics?.isRemovable;
+    $: isReadonly = ! isEditable;
+    $: hasViewerMessage = !_.isEmpty(usageCharacteristics.warningMessageForViewers);
+    $: hasEditorMessage = !_.isEmpty(usageCharacteristics.warningMessageForEditors);
+    $: hasMapping= !_.isEmpty(usageCharacteristics);
+
+</script>
 
-{#if !isConcrete && !_.isEmpty(usageCharacteristics)}
+{#if !isConcrete && hasMapping}
     <span class="waltz-error-icon" title="This data type is non-concrete so should not be mapped to">
         <Icon name="exclamation-triangle"
               style="vertical-align: middle"/>
     </span>
 {/if}
-{#if isEditMode && !_.isEmpty(usageCharacteristics.warningMessageForEditors)}
+{#if isEditMode && hasEditorMessage}
     <span class="waltz-warning-icon" title={usageCharacteristics.warningMessageForEditors}>
         <Icon name="exclamation-triangle"
               style="vertical-align: middle"/>
     </span>
 {/if}
-{#if !isEditMode && !_.isEmpty(usageCharacteristics.warningMessageForViewers)}
+{#if !isEditMode && hasViewerMessage}
     <span class="waltz-warning-icon" title={usageCharacteristics.warningMessageForViewers}>
         <Icon name="exclamation-triangle"
               style="vertical-align: middle"/>
     </span>
+{/if}
+{#if !isEditMode && isReadonly && hasViewerMessage}
+    <span title="read only" style="color: #777;">
+        <Icon name="lock"
+              style="vertical-align: middle"/>
+    </span>
+{/if}
+{#if isEditMode && isReadonly}
+    <span title="read only" style="color: #777;">
+        <Icon name="lock"
+              style="vertical-align: middle"/>
+    </span>
 {/if}
\ No newline at end of file