diff --git a/masp-profile/profile-crate/index.html b/masp-profile/profile-crate/index.html
index 0179c12..675a6f7 100644
--- a/masp-profile/profile-crate/index.html
+++ b/masp-profile/profile-crate/index.html
@@ -1238,7 +1238,7 @@ <h1>References</h1>
 <br>
 <h1>Examples</h1>
 <p><a href="https://www.mpi.nl/ISLE/documents/docs_frame.html">https://www.mpi.nl/ISLE/documents/docs_frame.html</a></p>
-<p><strong>30</strong> classes &middot; <strong>101</strong> properties</p>
+<p><strong>30</strong> classes &middot; <strong>102</strong> properties</p>
 <div class="row">
   <div class="col-md-6 col-panel">
     <h3>Classes</h3>
@@ -1281,6 +1281,7 @@ <h3>Properties</h3>
     <input class="entity-filter" type="search" placeholder="Filter properties…" data-target="prop-list">
     <ul id="prop-list" class="entity-list">
 <li><a href="#README.id" title="#README.id">@id</a> — README file <small style="color:#aaa">#README.id</small></li>
+<li><a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a> <small style="color:#aaa">#property_CreativeWork_README.id</small></li>
 <li><a href="#RO-Crate_Metadata_Descriptor.about" title="#RO-Crate_Metadata_Descriptor.about">About</a> — This property on the RO-Crate Metadata Descriptor references the Root Data Entity. In a SoSS+ profile there may be Schemas present for more than one 'flavour' of Root Data Entity with different @type arrays or `@conformsTo` references (or other specializations). <small style="color:#aaa">#RO-Crate_Metadata_Descriptor.about</small></li>
 <li><a href="#prop_ldac:access_DataReuseLicense" title="#prop_ldac:access_DataReuseLicense">Access</a> — Whether this is an open or restricted access license. <small style="color:#aaa">#prop_ldac:access_DataReuseLicense</small></li>
 <li><a href="#prop_ldac:accessControlList_DataReuseLicense" title="#prop_ldac:accessControlList_DataReuseLicense">Access Control List</a> — When a license has an authorizationWorkflow property with a value of the DefinedTerm AccessControlList this property has a URI value that points to a list of userIDs. <small style="color:#aaa">#prop_ldac:accessControlList_DataReuseLicense</small></li>
@@ -3337,8 +3338,8 @@ <h3><a id="RO-Crate_Metadata_Descriptor" title="#RO-Crate_Metadata_Descriptor"><
 <td></td>
 <td>Yes</td>
 <td>This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'.</td>
-<td><a href="#Root_Data_Entity" title="#Root_Data_Entity">Root Data Entity</a></td>
-<td>ro-crate-metadata.json</td>
+<td><a href="#propertyValue_RO-Crate_Metadata_Descriptor.id" title="#propertyValue_RO-Crate_Metadata_Descriptor.id">RO-Crate Metadadata Descriptor Identifier Constraint</a></td>
+<td></td>
 </tr>
 </tbody>
 </table>
@@ -3385,8 +3386,8 @@ <h3><a id="README_Entity" title="#README_Entity"></a> Class: README Entity</h3>
 <td></td>
 <td>Yes</td>
 <td>There must with the path <code>README.html</code> in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of <code>README.html</code>.</td>
-<td><a href="#README_Entity" title="#README_Entity">README Entity</a></td>
-<td>README.html</td>
+<td><a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a></td>
+<td></td>
 </tr>
 </tbody>
 </table>
@@ -3479,8 +3480,29 @@ <h3><a id="README.id" title="#README.id"></a> Property: @id</h3>
 <td><a href="#README.id" title="#README.id">@id</a></td>
 <td></td>
 <td>There must with the path <code>README.html</code> in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of <code>README.html</code>.</td>
+<td><a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a></td>
 <td><a href="#README_Entity" title="#README_Entity">README Entity</a></td>
-<td><a href="#README_Entity" title="#README_Entity">README Entity</a></td>
+</tr>
+</tbody>
+</table>
+<h3><a id="property_CreativeWork_README.id" title="#property_CreativeWork_README.id"></a> Property: @id</h3>
+<table>
+<thead>
+<tr>
+<th>Property</th>
+<th>Specialization Of</th>
+<th>Description</th>
+<th>Range</th>
+<th>Occurs in Domain(s)</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td><a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a></td>
+<td></td>
+<td>README file must have an @id matching /^readme.md$/i.</td>
+<td><a href="#propertyValue_property_CreativeWork_README.id" title="#propertyValue_property_CreativeWork_README.id">propertyValue_property_CreativeWork_README.id</a></td>
+<td><a href="#class_CreativeWork_README" title="#class_CreativeWork_README">class_CreativeWork_README</a></td>
 </tr>
 </tbody>
 </table>
@@ -4529,7 +4551,7 @@ <h3><a id="RO-Crate_Metadata_Descriptor.id" title="#RO-Crate_Metadata_Descriptor
 <td><a href="#RO-Crate_Metadata_Descriptor.id" title="#RO-Crate_Metadata_Descriptor.id">@id</a></td>
 <td></td>
 <td>This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'.</td>
-<td><a href="#Root_Data_Entity" title="#Root_Data_Entity">Root Data Entity</a></td>
+<td><a href="#propertyValue_RO-Crate_Metadata_Descriptor.id" title="#propertyValue_RO-Crate_Metadata_Descriptor.id">RO-Crate Metadadata Descriptor Identifier Constraint</a></td>
 <td><a href="#RO-Crate_Metadata_Descriptor" title="#RO-Crate_Metadata_Descriptor">RO-Crate Metadata Descriptor</a></td>
 </tr>
 </tbody>
diff --git a/masp-profile/profile-crate/profile-documentation.md b/masp-profile/profile-crate/profile-documentation.md
index 8250864..ee17fd1 100644
--- a/masp-profile/profile-crate/profile-documentation.md
+++ b/masp-profile/profile-crate/profile-documentation.md
@@ -1176,7 +1176,7 @@ At least 1 instances of this type MUST be present in the crate.
 | -------- | ----------------- | -------- | ----------- | ----- | ----- |
 | @type |  | Yes |  |  | <a href="http://schema.org/CreativeWork" title="http://schema.org/CreativeWork" target="_blank" rel="noopener">CreativeWork</a> |
 | <a href="#RO-Crate_Metadata_Descriptor.about" title="#RO-Crate_Metadata_Descriptor.about">about</a> | <a href="http://schema.org/about" target="_blank" rel="noopener">http://schema.org/about</a> | Yes | This property on the RO-Crate Metadata Descriptor references the Root Data Entity. In a SoSS+ profile there may be Schemas present for more than one 'flavour' of Root Data Entity with different @type arrays or `@conformsTo` references (or other specializations). | <a href="#Root_Data_Entity" title="#Root_Data_Entity">Root Data Entity</a> |  |
-| <a href="#RO-Crate_Metadata_Descriptor.id" title="#RO-Crate_Metadata_Descriptor.id">@id</a> |  | Yes | This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'. | <a href="#Root_Data_Entity" title="#Root_Data_Entity">Root Data Entity</a> | ro-crate-metadata.json |
+| <a href="#RO-Crate_Metadata_Descriptor.id" title="#RO-Crate_Metadata_Descriptor.id">@id</a> |  | Yes | This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'. | <a href="#propertyValue_RO-Crate_Metadata_Descriptor.id" title="#propertyValue_RO-Crate_Metadata_Descriptor.id">RO-Crate Metadadata Descriptor Identifier Constraint</a> |  |
 
 
 ### <a id="README_Entity" title="#README_Entity"></a> Class: README Entity
@@ -1194,7 +1194,7 @@ At least 1 instances of this type MUST be present in the crate.
 | Property | Specialization Of | Required | Description | Range | Value |
 | -------- | ----------------- | -------- | ----------- | ----- | ----- |
 | @type |  | Yes |  |  | <a href="http://schema.org/MediaObject" title="http://schema.org/MediaObject" target="_blank" rel="noopener">MediaObject</a> |
-| <a href="#README.id" title="#README.id">@id</a> |  | Yes | There must with the path `README.html` in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of `README.html`. | <a href="#README_Entity" title="#README_Entity">README Entity</a> | README.html |
+| <a href="#README.id" title="#README.id">@id</a> |  | Yes | There must with the path `README.html` in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of `README.html`. | <a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a> |  |
 
 
 ### <a id="Root_Data_Entity" title="#Root_Data_Entity"></a> Class: Root Data Entity
@@ -1223,7 +1223,12 @@ At least 1 instances of this type MUST be present in the crate.
 
 | Property | Specialization Of | Description | Range | Occurs in Domain(s) |
 | -------- | ----------------- | ----------- | ----------- | ----------- |
-| <a href="#README.id" title="#README.id">@id</a> |  | There must with the path `README.html` in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of `README.html`. | <a href="#README_Entity" title="#README_Entity">README Entity</a> | <a href="#README_Entity" title="#README_Entity">README Entity</a> |
+| <a href="#README.id" title="#README.id">@id</a> |  | There must with the path `README.html` in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of `README.html`. | <a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a> | <a href="#README_Entity" title="#README_Entity">README Entity</a> |
+### <a id="property_CreativeWork_README.id" title="#property_CreativeWork_README.id"></a> Property: @id
+
+| Property | Specialization Of | Description | Range | Occurs in Domain(s) |
+| -------- | ----------------- | ----------- | ----------- | ----------- |
+| <a href="#property_CreativeWork_README.id" title="#property_CreativeWork_README.id">@id</a> |  | README file must have an @id matching /^readme\.md$/i. | <a href="#propertyValue_property_CreativeWork_README.id" title="#propertyValue_property_CreativeWork_README.id">propertyValue_property_CreativeWork_README.id</a> | <a href="#class_CreativeWork_README" title="#class_CreativeWork_README">class_CreativeWork_README</a> |
 ### <a id="RO-Crate_Metadata_Descriptor.about" title="#RO-Crate_Metadata_Descriptor.about"></a> Property: About
 
 | Property | Specialization Of | Description | Range | Occurs in Domain(s) |
@@ -1473,7 +1478,7 @@ At least 1 instances of this type MUST be present in the crate.
 
 | Property | Specialization Of | Description | Range | Occurs in Domain(s) |
 | -------- | ----------------- | ----------- | ----------- | ----------- |
-| <a href="#RO-Crate_Metadata_Descriptor.id" title="#RO-Crate_Metadata_Descriptor.id">@id</a> |  | This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'. | <a href="#Root_Data_Entity" title="#Root_Data_Entity">Root Data Entity</a> | <a href="#RO-Crate_Metadata_Descriptor" title="#RO-Crate_Metadata_Descriptor">RO-Crate Metadata Descriptor</a> |
+| <a href="#RO-Crate_Metadata_Descriptor.id" title="#RO-Crate_Metadata_Descriptor.id">@id</a> |  | This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'. | <a href="#propertyValue_RO-Crate_Metadata_Descriptor.id" title="#propertyValue_RO-Crate_Metadata_Descriptor.id">RO-Crate Metadadata Descriptor Identifier Constraint</a> | <a href="#RO-Crate_Metadata_Descriptor" title="#RO-Crate_Metadata_Descriptor">RO-Crate Metadata Descriptor</a> |
 ### <a id="prop_identifier_RepositoryObject" title="#prop_identifier_RepositoryObject"></a> Property: Identifier
 
 | Property | Specialization Of | Description | Range | Occurs in Domain(s) |
diff --git a/masp-profile/profile-crate/ro-crate-metadata.json b/masp-profile/profile-crate/ro-crate-metadata.json
index c01bf5d..bfefde2 100644
--- a/masp-profile/profile-crate/ro-crate-metadata.json
+++ b/masp-profile/profile-crate/ro-crate-metadata.json
@@ -1150,12 +1150,25 @@
       },
       "rdfs:comment": "README file",
       "rangeIncludes": {
-        "@id": "#README_Entity"
+        "@id": "#property_CreativeWork_README.id"
       },
       "sh:minCount": "1",
       "sh:maxCount": "1",
-      "description": "There must with the path `README.html` in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of `README.html`.",
-      "value": "README.html"
+      "description": "There must with the path `README.html` in the root of the RO-Crate, and it must be described by an entity of type README_Entity with an @id of `README.html`."
+    },
+     {
+      "@id": "#property_CreativeWork_README.id",
+      "@type": "rdf:Property",
+      "description": "README file must have an @id matching /^readme\\.md$/i.",
+      "rdfs:label": "@id",
+      "rangeIncludes": {
+        "@id": "#propertyValue_property_CreativeWork_README.id"
+      },
+      "domainIncludes": {
+        "@id": "#class_CreativeWork_README"
+      },
+      "sh:minCount": 1,
+      "sh:maxCount": 1
     },
     {
       "@id": "#Root_Data_Entity",
@@ -3354,16 +3367,24 @@
         "@id": "#RO-Crate_Metadata_Descriptor"
       },
       "rdfs:comment": "The RO-Crate Metadata Descriptor",
-      "rangeIncludes": {
-        "@id": "#Root_Data_Entity"
+       "rangeIncludes": {
+        "@id": "#propertyValue_RO-Crate_Metadata_Descriptor.id"
       },
       "sh:minCount": "1",
       "isPartOf": {
         "@id": "#hasSpecializedSchema"
       },
       "sh:maxCount": "1",
-      "description": "This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'.",
-      "value": "ro-crate-metadata.json"
+      "description": "This is the 'magic' entity that identifies the RO-Crate Metadata Descriptor, which is the root of the graph and the entry point for validation. It must have a @type of RO-Crate_Metadata_Descriptor and its @id must be 'ro-crate-metadata.json'."
+    },
+     {
+      "@id": "#propertyValue_RO-Crate_Metadata_Descriptor.id",
+      "@type": "PropertyValue",
+      "name": "RO-Crate Metadadata Descriptor Identifier Constraint",
+      "description": "Allowed identifier value constraint for RO-Crate Metadadata Descriptor.",
+      "value": "ro-crate-metadata.json",
+      "sh:minCount": 1,
+      "sh:maxCount": 1
     },
     {
       "@id": "ldac:AccessControlList",
@@ -4188,4 +4209,4 @@
       "name": "Language Data Commons RO-Crate Profile: Collection"
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/masp-schema/schema-crate/ro-crate-metadata.json b/masp-schema/schema-crate/ro-crate-metadata.json
index a7f9944..c9cdeb0 100644
--- a/masp-schema/schema-crate/ro-crate-metadata.json
+++ b/masp-schema/schema-crate/ro-crate-metadata.json
@@ -1,4 +1,4 @@
-{
+
   "@context": [
     "https://w3id.org/ro/crate/1.2/context",
     {