diff --git a/ccm-core/src/main/java/org/libreccm/categorization/Domain.java b/ccm-core/src/main/java/org/libreccm/categorization/Domain.java
index 109446a17..be258a0ad 100644
--- a/ccm-core/src/main/java/org/libreccm/categorization/Domain.java
+++ b/ccm-core/src/main/java/org/libreccm/categorization/Domain.java
@@ -42,12 +42,10 @@ import static org.libreccm.core.CoreConstants.DB_SCHEMA;
 
 import org.libreccm.imexport.Exportable;
 
-import java.text.DateFormat;
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Date;
 import java.util.List;
 import java.util.Objects;
 
@@ -66,8 +64,6 @@ import javax.persistence.NamedQuery;
 import javax.persistence.NamedSubgraph;
 import javax.persistence.OneToMany;
 import javax.persistence.Table;
-import javax.persistence.Temporal;
-import javax.persistence.TemporalType;
 import javax.validation.constraints.NotBlank;
 
 /**
@@ -191,7 +187,6 @@ public class Domain extends CcmObject implements Serializable, Exportable {
      * A version string for the {@code Domain}.
      */
     @Column(name = "VERSION", nullable = true)
-    @NotBlank
     @XmlElement(name = "version", namespace = CAT_XML_NS)
     private String version;
 
@@ -199,7 +194,6 @@ public class Domain extends CcmObject implements Serializable, Exportable {
      * A timestamp for the release date of the {@code Domain}.
      */
     @Column(name = "RELEASED")
-//    @Temporal(TemporalType.TIMESTAMP)
     @XmlElement(name = "released", namespace = CAT_XML_NS)
     private LocalDate released;
 
diff --git a/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemDetailsModel.java b/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemDetailsModel.java
index 60cea6cd9..5d88c690e 100644
--- a/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemDetailsModel.java
+++ b/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemDetailsModel.java
@@ -181,7 +181,7 @@ public class CategorySystemDetailsModel {
         if (domain.getReleased() == null) {
             released = "";
         } else {
-            released = DateTimeFormatter.ISO_DATE_TIME
+            released = DateTimeFormatter.ISO_DATE
                 .withZone(ZoneOffset.systemDefault())
                 .format(domain.getReleased());
         }
diff --git a/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemFormController.java b/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemFormController.java
index fa1daccaf..b476c6015 100644
--- a/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemFormController.java
+++ b/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemFormController.java
@@ -98,7 +98,7 @@ public class CategorySystemFormController {
             categorySystemDetailsModel.addMessage(
                 new Message(
                     adminMessages.get("categorysystems.form.errors.uri_invalid"),
-                    MessageType.PRIMARY)
+                    MessageType.DANGER)
             );
             categorySystemDetailsModel.addInvalidField("uri");
             return "org/libreccm/ui/admin/categories/categorysystem-form.xhtml";
@@ -157,7 +157,7 @@ public class CategorySystemFormController {
                     new Message(
                         adminMessages.get(
                             "categorysystems.form.errors.uri_invalid"),
-                        MessageType.PRIMARY)
+                        MessageType.DANGER)
                 );
                 categorySystemDetailsModel.addInvalidField("uri");
                 return "org/libreccm/ui/admin/categories/categorysystem-form.xhtml";
diff --git a/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemsTableModel.java b/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemsTableModel.java
index 9195f8ed4..516bb12be 100644
--- a/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemsTableModel.java
+++ b/ccm-core/src/main/java/org/libreccm/ui/admin/categories/CategorySystemsTableModel.java
@@ -24,6 +24,7 @@ import org.libreccm.core.CoreConstants;
 import org.libreccm.security.AuthorizationRequired;
 import org.libreccm.security.RequiresPrivilege;
 
+import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -65,9 +66,9 @@ public class CategorySystemsTableModel {
         row.setVersion(domain.getVersion());
         if (domain.getReleased() != null) {
             row.setReleased(
-                DateTimeFormatter.ISO_DATE_TIME.format(
-                    domain.getReleased()
-                )
+                DateTimeFormatter.ISO_DATE
+                    .withZone(ZoneId.systemDefault())
+                    .format(domain.getReleased())
             );
         }
         row.setTitle(
diff --git a/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystem-form.xhtml b/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystem-form.xhtml
index 781d5f8d9..78db188a8 100644
--- a/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystem-form.xhtml
+++ b/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystem-form.xhtml
@@ -49,7 +49,7 @@
                             #{AdminMessages['categorysystems.form.domainKey.label']}
                         </label>
                         <input aria-describedby="domainKey-help"
-                               class="form-control"
+                               class="form-control #{CategorySystemDetailsModel.invalidFields.contains('domainKey') ? 'is-invalid' : ''}"
                                name="domainKey"
                                required="true"
                                type="text" 
@@ -64,7 +64,7 @@
                             #{AdminMessages['categorysystems.form.uri.label']}
                         </label>
                         <input aria-describedby="uri-help"
-                               class="form-control"
+                               class="form-control #{CategorySystemDetailsModel.invalidFields.contains('uri') ? 'is-invalid' : ''}"
                                name="uri"
                                type="text" 
                                value="#{CategorySystemDetailsModel.uri}"
@@ -79,7 +79,7 @@
                             #{AdminMessages['categorysystems.form.version.label']}
                         </label>
                         <input aria-describedby="version-help"
-                               class="form-control"
+                               class="form-control #{CategorySystemDetailsModel.invalidFields.contains('version') ? 'is-invalid' : ''}"
                                name="version"
                                type="text" 
                                value="#{CategorySystemDetailsModel.version}"
@@ -94,7 +94,7 @@
                             #{AdminMessages['categorysystems.form.released.label']}
                         </label>
                         <input aria-describedby="released-help"
-                               class="form-control"
+                               class="form-control #{CategorySystemDetailsModel.invalidFields.contains('released') ? 'is-invalid' : ''}"
                                name="released"
                                type="date" 
                                value="#{CategorySystemDetailsModel.released}"
diff --git a/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystems.xhtml b/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystems.xhtml
index f9dec4e84..6df5addce 100644
--- a/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystems.xhtml
+++ b/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/categories/categorysystems.xhtml
@@ -1,4 +1,4 @@
-    <!DOCTYPE html>
+<!DOCTYPE html [<!ENTITY times '&#215;'>]>
 <html xmlns="http://www.w3.org/1999/xhtml" 
       xmlns:c="http://xmlns.jcp.org/jsp/jstl/core"
       xmlns:h="http://xmlns.jcp.org/jsf/html"
@@ -32,7 +32,7 @@
                              width="1em"
                              height="1em"
                              fill="currentColor">
-                            <use xlink:href="#{request.contextPath}/assets/bootstrap/bootstrap-icons.svg#circle-plus" />
+                            <use xlink:href="#{request.contextPath}/assets/bootstrap/bootstrap-icons.svg#plus-circle" />
                         </svg>
                         <span>#{AdminMessages['categorysystems.add']}</span>
                     </a>
@@ -44,20 +44,83 @@
                             <th>#{AdminMessages['categorysystems.table.headers.uri']}</th>
                             <th>#{AdminMessages['categorysystems.table.headers.version']}</th>
                             <th>#{AdminMessages['categorysystems.table.headers.released']}</th>
+                            <th class="text-center" colspan="2">
+                                #{AdminMessages['categorysystems.table.headers.actions']}
+                            </th>
                         </tr>
                     </thead>
                     <tbody>
                         <c:forEach items="#{CategorySystemsTableModel.categorySystems}" 
                                    var="categorySystem">
                             <tr>
-                                <td>
-                                    <a href="#{mvc.uri('CategorySystemsController#getCategorySystemDetails', { 'categorySystemIdentifier': categorySystem.identifier })}">
-                                    #{categorySystem.domainKey}
-                                    </a>
-                                </td>
+                                <td>#{categorySystem.domainKey}</td>
                                 <td>#{categorySystem.uri}</td>
                                 <td>#{categorySystem.version}</td>
                                 <td>#{categorySystem.released}</td>
+                                <td>
+                                    <a class="btn btn-info"
+                                       href="#{mvc.uri('CategorySystemsController#getCategorySystemDetails', { 'categorySystemIdentifier': categorySystem.identifier })}">
+                                        <svg class="bi"
+                                             width="1em"
+                                             height="1em"
+                                             fill="currentColor">
+                                            <use xlink:href="#{request.contextPath}/assets/bootstrap/bootstrap-icons.svg#pen" />
+                                        </svg>
+                                        #{AdminMessages['categorysystems.table.actions.edit']}
+                                    </a>
+                                </td>
+                                <td>
+                                    <button class="btn btn-danger"
+                                            data-target="#confirm-delete-#{categorySystem.identifier}"
+                                            data-toggle="modal"
+                                            type="button">
+                                        <svg class="bi"
+                                             width="1em"
+                                             height="1em"
+                                             fill="currentColor">
+                                            <use xlink:href="#{request.contextPath}/assets/bootstrap/bootstrap-icons.svg#x-circle" />
+                                        </svg>
+                                        #{AdminMessages['categorysystems.table.actions.delete']}
+                                    </button>
+                                    <div class="modal"
+                                         id="confirm-delete-#{categorySystem.identifier}"
+                                         tabindex="-1">
+                                        <div class="modal-dialog">
+                                            <form action="#{mvc.uri('CategorySystemsController#deleteCategorySystem', {'categorySystemIdentifier': categorySystem.identifier })}"
+                                                  class="modal-content"
+                                                  method="post">
+                                                <div class="modal-header">
+                                                    <h3 class="modal-title">
+                                                        #{AdminMessages['categorysystems.delete.confirm.title']}
+                                                    </h3>
+                                                    <button aria-label="#{AdminMessages['usersgroupsroles.groups.delete.confirm.cancel']}"
+                                                            class="close" 
+                                                            data-dismiss="modal" 
+                                                            type="button">
+                                                        <span aria-hidden="true">&times;</span>
+                                                    </button>
+                                                </div>
+                                                <div class="modal-body">
+                                                    #{AdminMessages.getMessage('categorysystems.delete.confirm.message', [categorySystem.identifier])}
+                                                    <input name="confirmed"
+                                                           type="hidden"
+                                                           value="true" />
+                                                </div>
+                                                <div class="modal-footer">
+                                                    <button class="btn btn-secondary"
+                                                            data-dismiss="modal"
+                                                            type="button">
+                                                        #{AdminMessages['categorysystems.delete.confirm.cancel']}
+                                                    </button>
+                                                    <button class="btn btn-danger" 
+                                                            type="submit">
+                                                        #{AdminMessages['categorysystems.delete.confirm.yes']}
+                                                    </button>
+                                                </div>
+                                            </form>
+                                        </div>
+                                    </div>
+                                </td>
                             </tr>
                         </c:forEach>
                     </tbody>
diff --git a/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/users-groups-roles/groups.xhtml b/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/users-groups-roles/groups.xhtml
index fe90baa6f..de27f6318 100644
--- a/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/users-groups-roles/groups.xhtml
+++ b/ccm-core/src/main/resources/WEB-INF/views/org/libreccm/ui/admin/users-groups-roles/groups.xhtml
@@ -67,8 +67,7 @@
                                 <td class="text-center action-col">
                                     <button class="btn btn-danger"
                                             data-toggle="modal"
-                                            data-target="#confirm-delete-#{group.name}"
-                                            href="#">
+                                            data-target="#confirm-delete-#{group.name}">
                                         <svg class="bi"
                                              width="1em"
                                              height="1em"
diff --git a/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle.properties b/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle.properties
index d81275984..059e1b992 100644
--- a/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle.properties
+++ b/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle.properties
@@ -294,3 +294,10 @@ categorysystems.form.released.label=Released
 categorysystems.details.version=Version
 categorysystems.details.released=Released
 categorysystems.form.errors.uri_invalid=URI is invalid
+categorysystems.table.headers.actions=Actions
+categorysystems.table.actions.delete=Delete
+categorysystems.table.actions.edit=Edit
+categorysystems.delete.confirm.title=Confirm Delete
+categorysystems.delete.confirm.message=Are you sure to delete the category system {0} and all its categories?
+categorysystems.delete.confirm.cancel=Cancel
+categorysystems.delete.confirm.yes=Delete Category System
diff --git a/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle_de.properties b/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle_de.properties
index 9664bc61e..6816d7078 100644
--- a/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle_de.properties
+++ b/ccm-core/src/main/resources/org/libreccm/ui/AdminBundle_de.properties
@@ -294,3 +294,10 @@ categorysystems.form.released.label=Released
 categorysystems.details.version=Version
 categorysystems.details.released=Freigegeben
 categorysystems.form.errors.uri_invalid=URI ist nicht valide
+categorysystems.table.headers.actions=Aktionen
+categorysystems.table.actions.delete=L\u00f6schen
+categorysystems.table.actions.edit=Bearbeiten
+categorysystems.delete.confirm.title=L\u00f6schen best\u00e4tigen
+categorysystems.delete.confirm.message=Sind Sie sicher, dass Sie das Kategoriensystem {0} mit allen seinen Kategorien l\u00f6schen wollen?
+categorysystems.delete.confirm.cancel=Abbrechen
+categorysystems.delete.confirm.yes=Kategoriensystem l\u00f6schen