diff --git a/administrator/components/com_jedchecker/language/en-GB/en-GB.com_jedchecker.ini b/administrator/components/com_jedchecker/language/en-GB/en-GB.com_jedchecker.ini
index 9928477..801ba32 100644
--- a/administrator/components/com_jedchecker/language/en-GB/en-GB.com_jedchecker.ini
+++ b/administrator/components/com_jedchecker/language/en-GB/en-GB.com_jedchecker.ini
@@ -93,3 +93,18 @@ COM_JEDCHECKER_EMPTY_UPLOAD_FIELD="Please, select a zipped file to be uploaded"
 COM_JEDCHECKER_TOOLBAR_CHECK="Check"
 COM_JEDCHECKER_TOOLBAR_CLEAR="Clear"
 COM_JEDCHECKER_CLICK_TO_VIEW_DETAILS="Click to View Details"
+COM_JEDCHECKER_MANIFEST="XML Manifests"
+COM_JEDCHECKER_MANIFEST_DESC="Validation of extension's XML manifest file"
+COM_JEDCHECKER_MANIFEST_UNKNOWN_TYPE="Unknown extension type: %s"
+COM_JEDCHECKER_MANIFEST_TYPE_NOT_ACCEPTED="Extension type '%s' is not accepted by JED"
+COM_JEDCHECKER_MANIFEST_UNKNOWN_ATTRIBUTE="Node <%1$s> has unknown attribute '%2$s'"
+COM_JEDCHECKER_MANIFEST_UNKNOWN_CHILDREN="Node <%s> has unknown child element"
+COM_JEDCHECKER_MANIFEST_MISSED_REQUIRED="Node <%1$s> doesn't contain required <%2$s> element"
+COM_JEDCHECKER_MANIFEST_MISSED_OPTIONAL="Node <%1$s> doesn't contain optional <%2$s> element"
+COM_JEDCHECKER_MANIFEST_MULTIPLE_FOUND="Node <%1$s> contains multiple <%2$s> elements"
+COM_JEDCHECKER_MANIFEST_UNKNOWN_CHILD="Node <%1$s> contains unknown <%2$s> element"
+COM_JEDCHECKER_MANIFEST_EMPTY_CHILD="Found empty <%s> element"
+COM_JEDCHECKER_MANIFEST_MENU_UNUSED_ATTRIBUTE="Menu item attribute '%s' is not used with 'link' attribute"
+COM_JEDCHECKER_MANIFEST_MISSED_METHOD_UPGRADE="Without the method="upgrade" attribute the extension package cannot be upgraded"
+COM_JEDCHECKER_MANIFEST_MISSED_ATTRIBUTE="The node <%1$s> doesn't contain required '%2$s' attribute"
+COM_JEDCHECKER_MANIFEST_UNKNOWN_ATTRIBUTE_VALUE="The node <%1$s> has attribute '%2$s' with unknown value "%3$s""
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest.php b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest.php
new file mode 100644
index 0000000..5d4f119
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest.php
@@ -0,0 +1,404 @@
+<?php
+/**
+ * @package    Joomla.JEDChecker
+ *
+ * @copyright  Copyright (C) 2021 Open Source Matters, Inc. All rights reserved.
+ *
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+defined('_JEXEC') or die('Restricted access');
+
+
+// Include the rule base class
+require_once JPATH_COMPONENT_ADMINISTRATOR . '/models/rule.php';
+
+
+/**
+ * class JedcheckerRulesXMLManifest
+ *
+ * This class validates all XML manifests
+ *
+ * @since  2.3
+ */
+class JedcheckerRulesXMLManifest extends JEDcheckerRule
+{
+	/**
+	 * The formal ID of this rule. For example: SE1.
+	 *
+	 * @var    string
+	 */
+	protected $id = 'MANIFEST';
+
+	/**
+	 * The title or caption of this rule.
+	 *
+	 * @var    string
+	 */
+	protected $title = 'COM_JEDCHECKER_MANIFEST';
+
+	/**
+	 * The description of this rule.
+	 *
+	 * @var    string
+	 */
+	protected $description = 'COM_JEDCHECKER_MANIFEST_DESC';
+
+	/**
+	 * List of errors.
+	 *
+	 * @var    string[]
+	 */
+	protected $errors;
+
+	/**
+	 * List of warnings.
+	 *
+	 * @var    string[]
+	 */
+	protected $warnings;
+
+	/**
+	 * List of infos.
+	 *
+	 * @var    string[]
+	 */
+	protected $infos;
+
+	/**
+	 * Rules for XML nodes
+	 *   ? - single, optional
+	 *   = - single, required, warning if missed
+	 *   ! - single, required, error if missed
+	 *   * - multiple, optional
+	 * @var array
+	 */
+	protected $DTDNodeRules;
+
+	/**
+	 * Rules for attributes
+	 *   (list of allowed attributes)
+	 * @var array
+	 */
+	protected $DTDAttrRules;
+
+	/**
+	 * List of extension types
+	 *
+	 * @var string[]
+	 */
+	protected $joomlaTypes = array(
+		'component', 'file', 'language', 'library',
+		'module', 'package', 'plugin', 'template'
+	);
+
+	/**
+	 * List of JED extension types
+	 *
+	 * @var string[]
+	 */
+	protected $jedTypes = array(
+		'component', 'module', 'package', 'plugin'
+	);
+
+	/**
+	 * Initiates the search and check
+	 *
+	 * @return    void
+	 */
+	public function check()
+	{
+		// Find all XML files of the extension
+		$files = JFolder::files($this->basedir, '\.xml$', true, true);
+
+		// Iterate through all the xml files
+		foreach ($files as $file)
+		{
+			// Try to check the file
+			$this->find($file);
+		}
+	}
+
+	/**
+	 * Reads a file and validate XML manifest
+	 *
+	 * @param   string  $file  - The path to the file
+	 *
+	 * @return boolean True if the manifest file was found, otherwise False.
+	 */
+	protected function find($file)
+	{
+		$xml = simplexml_load_file($file);
+
+		// Failed to parse the xml file.
+		// Assume that this is not a extension manifest
+		if (!$xml)
+		{
+			return false;
+		}
+
+		// Check if this is an extension manifest
+		if ($xml->getName() !== 'extension')
+		{
+			return false;
+		}
+
+		// Check extension type
+		$type = (string) $xml['type'];
+
+		if (!in_array($type, $this->joomlaTypes, true))
+		{
+			$this->report->addError($file, JText::sprintf('COM_JEDCHECKER_MANIFEST_UNKNOWN_TYPE', $type));
+
+			return true;
+		}
+
+		// JED allows components, modules, plugins, and packages (as a container) only
+		if (!in_array($type, $this->jedTypes, true))
+		{
+			$this->report->addError($file, JText::sprintf('COM_JEDCHECKER_MANIFEST_TYPE_NOT_ACCEPTED', $type));
+		}
+
+		// Load DTD-like data for this extension type
+		$jsonFilename = __DIR__ . '/xmlmanifest/dtd_' . $type . '.json';
+
+		if (!is_file($jsonFilename))
+		{
+			return true;
+		}
+
+		// Warn if method="upgrade" attribute is not found
+		if ((string) $xml['method'] !== 'upgrade')
+		{
+			$this->report->addWarning($file, JText::_('COM_JEDCHECKER_MANIFEST_MISSED_METHOD_UPGRADE'));
+		}
+
+		// Check 'client' attribute is "site" or "administrator" (for module/template only)
+		if ($type === 'module' || $type === 'template')
+		{
+			$client = (string) $xml['client'];
+
+			if (!isset($xml['client']))
+			{
+				$this->report->addError($file, JText::sprintf('COM_JEDCHECKER_MANIFEST_MISSED_ATTRIBUTE', $xml->getName(), 'client'));
+			}
+			elseif ($client !== 'site' && $client !== 'administrator')
+			{
+				$this->report->addError($file, JText::sprintf('COM_JEDCHECKER_MANIFEST_UNKNOWN_ATTRIBUTE_VALUE', $xml->getName(), 'client', $client));
+			}
+		}
+
+		$data = json_decode(file_get_contents($jsonFilename), true);
+		$this->DTDNodeRules = $data['nodes'];
+		$this->DTDAttrRules = $data['attributes'];
+
+		$this->errors = array();
+		$this->warnings = array();
+		$this->infos = array();
+
+		// Validate manifest
+		$this->validateXml($xml, 'extension');
+
+		if (count($this->errors))
+		{
+			$this->report->addError($file, implode('<br />', $this->errors));
+		}
+
+		if (count($this->warnings))
+		{
+			$this->report->addWarning($file, implode('<br />', $this->warnings));
+		}
+
+		if (count($this->infos))
+		{
+			$this->report->addInfo($file, implode('<br />', $this->infos));
+		}
+
+		// All checks passed. Return true
+		return true;
+	}
+
+	/**
+	 * @param   SimpleXMLElement  $node        XML node object
+	 * @param   string            $ruleset     rulest name in the DTD array
+	 *
+	 * @return  void
+	 */
+	protected function validateXml($node, $ruleset)
+	{
+		// Get node name
+		$name = $node->getName();
+
+		// Check attributes
+		$DTDattributes = isset($this->DTDAttrRules[$ruleset]) ? $this->DTDAttrRules[$ruleset] : array();
+
+		if (count($DTDattributes) === 0)
+		{
+			// No known attributes for this node
+			foreach ($node->attributes() as $attr)
+			{
+				$this->infos[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_UNKNOWN_ATTRIBUTE', $name, (string) $attr->getName());
+			}
+		}
+		elseif ($DTDattributes[0] !== '*') // Skip node with arbitrary attributes (e.g. "field")
+		{
+			foreach ($node->attributes() as $attr)
+			{
+				$attrName = (string) $attr->getName();
+
+				if (!in_array($attrName, $DTDattributes, true))
+				{
+					// The node has unknown attribute
+					$this->infos[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_UNKNOWN_ATTRIBUTE', $name, $attrName);
+				}
+			}
+		}
+
+		// Check children nodes
+		$DTDchildRules = isset($this->DTDNodeRules[$ruleset]) ? $this->DTDNodeRules[$ruleset] : array();
+
+		// Child node name to ruleset name mapping
+		$DTDchildToRule = array();
+
+		if (count($DTDchildRules) === 0)
+		{
+			// No known children for this node
+			if ($node->count() > 0)
+			{
+				$this->infos[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_UNKNOWN_CHILDREN', $name);
+			}
+		}
+		elseif (!isset($DTDchildRules['*'])) // Skip node with arbitrary children
+		{
+			// 1) check required single elements
+			foreach ($DTDchildRules as $childRuleset => $mode)
+			{
+				$child = $childRuleset;
+
+				if (strpos($child, ':') !== false)
+				{
+					// Split ruleset name into a prefix and the child node name
+					list ($prefix, $child) = explode(':', $child, 2);
+				}
+
+				// Populate node-to-ruleset mapping
+				$DTDchildToRule[$child] = $childRuleset;
+
+				$count = $node->$child->count();
+
+				switch ($mode)
+				{
+					case '!':
+						if ($count === 0)
+						{
+							// The node doesn't contain required child element
+							$this->errors[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_MISSED_REQUIRED', $name, $child);
+						}
+						elseif ($count > 1)
+						{
+							// The node contains multiple child elements when single only is expected
+							$this->errors[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_MULTIPLE_FOUND', $name, $child);
+						}
+
+						break;
+
+					case '=':
+						if ($count === 0)
+						{
+							// The node doesn't contain optional child element
+							$this->infos[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_MISSED_OPTIONAL', $name, $child);
+						}
+						elseif ($count > 1)
+						{
+							// The node contains multiple child elements when single only is expected
+							$this->warnings[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_MULTIPLE_FOUND', $name, $child);
+						}
+
+						break;
+				}
+			}
+
+			// 2) check unknown/multiple elements
+
+			// Collect unique child node names
+			$childNames = array();
+
+			foreach ($node as $child)
+			{
+				$childNames[$child->getName()] = 1;
+			}
+
+			$childNames = array_keys($childNames);
+
+			foreach ($childNames as $child)
+			{
+				if (!isset($DTDchildToRule[$child]))
+				{
+					// The node contains unknown child element
+					$this->infos[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_UNKNOWN_CHILD', $name, $child);
+				}
+				else
+				{
+					if ($DTDchildRules[$DTDchildToRule[$child]] === '?' && $node->$child->count() > 1)
+					{
+						// The node contains multiple child elements when single only is expected
+						$this->errors[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_MULTIPLE_FOUND', $name, $child);
+					}
+				}
+			}
+
+			// 3) check empty elements
+			foreach ($node as $child)
+			{
+				if ($child->count() === 0 && $child->attributes()->count() === 0 && (string) $child === '')
+				{
+					$this->infos[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_EMPTY_CHILD', $child->getName());
+				}
+			}
+		}
+
+		// Extra checks (if exist)
+		$method = 'validateXml' . $name;
+
+		if (method_exists($this, $method))
+		{
+			$this->$method($node);
+		}
+
+		// Recursion
+		foreach ($node as $child)
+		{
+			$childName = $child->getName();
+
+			if (isset($DTDchildToRule[$childName]))
+			{
+				$this->validateXml($child, $DTDchildToRule[$childName]);
+			}
+		}
+	}
+
+	/**
+	 * Extra check for menu nodes
+	 * @param   SimpleXMLElement  $node  XML node
+	 *
+	 * @return void
+	 */
+	protected function validateXmlMenu($node)
+	{
+		if (isset($node['link']))
+		{
+			// The "link" attribute overrides any other link-related attributes (warn if they present)
+			$skipAttrs = array('act', 'controller', 'layout', 'sub', 'task', 'view');
+
+			foreach ($node->attributes() as $attr)
+			{
+				$attrName = $attr->getName();
+
+				if (in_array($attrName, $skipAttrs, true))
+				{
+					$this->warnings[] = JText::sprintf('COM_JEDCHECKER_MANIFEST_MENU_UNUSED_ATTRIBUTE', $attrName);
+				}
+			}
+		}
+	}
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_component.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_component.json
new file mode 100644
index 0000000..5ca36f4
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_component.json
@@ -0,0 +1,120 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "element": "?",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "scriptfile": "?",
+      "install": "?",
+      "update": "?",
+      "uninstall": "?",
+      "files": "?",
+      "languages": "?",
+      "media": "?",
+      "administration": "?",
+      "updateservers": "?",
+      "dlid": "?",
+      "config": "?",
+      "namespace": "?"
+    },
+    "administration": {
+      "menu": "?",
+      "submenu": "?",
+      "files": "=",
+      "languages": "?",
+      "media": "?"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "media": {
+      "filename": "*",
+      "media:file": "*",
+      "folder": "*"
+    },
+    "submenu": {
+      "menu": "*"
+    },
+    "install": {
+      "sql": "*"
+    },
+    "update": {
+      "sql": "*",
+      "schemas": "*"
+    },
+    "uninstall": {
+      "sql": "*"
+    },
+    "sql": {
+      "file": "*"
+    },
+    "schemas": {
+      "schemapath": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "media": [
+      "destination",
+      "folder"
+    ],
+    "menu": [
+      "act",
+      "controller",
+      "hidden",
+      "img",
+      "layout",
+      "link",
+      "sub",
+      "task",
+      "view"
+    ],
+    "file": [
+      "charset",
+      "driver"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "namespace": [
+      "path"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_file.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_file.json
new file mode 100644
index 0000000..902338e
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_file.json
@@ -0,0 +1,86 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "scriptfile": "?",
+      "install": "?",
+      "update": "?",
+      "uninstall": "?",
+      "fileset": "!",
+      "languages": "?",
+      "updateservers": "?",
+      "dlid": "?"
+    },
+    "fileset": {
+      "files": "*"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "install": {
+      "sql": "*"
+    },
+    "update": {
+      "sql": "*",
+      "schemas": "*"
+    },
+    "uninstall": {
+      "sql": "*"
+    },
+    "sql": {
+      "file": "*"
+    },
+    "schemas": {
+      "schemapath": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder",
+      "target"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "file": [
+      "charset",
+      "driver"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_language.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_language.json
new file mode 100644
index 0000000..ad20a0b
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_language.json
@@ -0,0 +1,68 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "tag": "!",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "files": "!",
+      "media": "?",
+      "fonts": "?",
+      "update": "?",
+      "updateservers": "?",
+      "dlid": "?"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "media": {
+      "filename": "*",
+      "media:file": "*",
+      "folder": "*"
+    },
+    "fonts": {
+      "filename": "*",
+      "fonts:file": "*",
+      "folder": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "media": [
+      "destination",
+      "folder"
+    ],
+    "fonts": [
+      "folder"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_library.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_library.json
new file mode 100644
index 0000000..b886e4f
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_library.json
@@ -0,0 +1,95 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "libraryname": "!",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "packager": "?",
+      "packagerurl": "?",
+      "scriptfile": "?",
+      "install": "?",
+      "update": "?",
+      "uninstall": "?",
+      "files": "?",
+      "languages": "?",
+      "media": "?",
+      "updateservers": "?",
+      "dlid": "?"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "media": {
+      "filename": "*",
+      "media:file": "*",
+      "folder": "*"
+    },
+    "install": {
+      "sql": "*"
+    },
+    "update": {
+      "sql": "*",
+      "schemas": "*"
+    },
+    "uninstall": {
+      "sql": "*"
+    },
+    "sql": {
+      "file": "*"
+    },
+    "schemas": {
+      "schemapath": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "media": [
+      "destination",
+      "folder"
+    ],
+    "file": [
+      "charset",
+      "driver"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_module.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_module.json
new file mode 100644
index 0000000..3becd97
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_module.json
@@ -0,0 +1,144 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "element": "?",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "scriptfile": "?",
+      "install": "?",
+      "update": "?",
+      "uninstall": "?",
+      "files": "?",
+      "languages": "?",
+      "media": "?",
+      "updateservers": "?",
+      "dlid": "?",
+      "config": "?",
+      "namespace": "?"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "media": {
+      "filename": "*",
+      "media:file": "*",
+      "folder": "*"
+    },
+    "install": {
+      "sql": "*"
+    },
+    "update": {
+      "sql": "*",
+      "schemas": "*"
+    },
+    "uninstall": {
+      "sql": "*"
+    },
+    "sql": {
+      "file": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    },
+    "config": {
+      "fields": "!"
+    },
+    "fields": {
+      "fieldset": "+"
+    },
+    "fieldset": {
+      "field": "+"
+    },
+    "field": {
+      "*": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "filename": [
+      "module"
+    ],
+    "files:file": [
+      "module"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "media": [
+      "destination",
+      "folder"
+    ],
+    "file": [
+      "charset",
+      "driver"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "namespace": [
+      "path"
+    ],
+    "config": [
+      "addfieldpath",
+      "addfieldprefix",
+      "addformpath",
+      "addformprefix",
+      "addrulepath",
+      "addruleprefix"
+    ],
+    "fields": [
+      "addfieldpath",
+      "addfieldprefix",
+      "addformpath",
+      "addformprefix",
+      "addrulepath",
+      "addruleprefix",
+      "name"
+    ],
+    "fieldset": [
+      "addfieldpath",
+      "addfieldprefix",
+      "addformpath",
+      "addformprefix",
+      "addrulepath",
+      "addruleprefix",
+      "description",
+      "label",
+      "name"
+    ],
+    "field": [
+      "*"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_package.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_package.json
new file mode 100644
index 0000000..f9a7930
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_package.json
@@ -0,0 +1,76 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "packagename": "!",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "scriptfile": "?",
+      "update": "?",
+      "files": "?",
+      "languages": "?",
+      "updateservers": "?",
+      "dlid": "?",
+      "url": "?",
+      "packager": "?",
+      "packagerurl": "?",
+      "blockChildUninstall": "?"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "files:file": [
+      "client",
+      "group",
+      "id",
+      "type"
+    ],
+    "filename": [
+      "client",
+      "group",
+      "id",
+      "type"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_plugin.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_plugin.json
new file mode 100644
index 0000000..1b5b555
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_plugin.json
@@ -0,0 +1,145 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "element": "?",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "scriptfile": "?",
+      "install": "?",
+      "update": "?",
+      "uninstall": "?",
+      "files": "?",
+      "languages": "?",
+      "media": "?",
+      "updateservers": "?",
+      "dlid": "?",
+      "config": "?",
+      "namespace": "?"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "media": {
+      "filename": "*",
+      "media:file": "*",
+      "folder": "*"
+    },
+    "install": {
+      "sql": "*"
+    },
+    "update": {
+      "sql": "*",
+      "schemas": "*"
+    },
+    "uninstall": {
+      "sql": "*"
+    },
+    "sql": {
+      "file": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    },
+    "config": {
+      "fields": "!"
+    },
+    "fields": {
+      "fieldset": "+"
+    },
+    "fieldset": {
+      "field": "+"
+    },
+    "field": {
+      "*": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "group",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "filename": [
+      "plugin"
+    ],
+    "files:file": [
+      "plugin"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "media": [
+      "destination",
+      "folder"
+    ],
+    "file": [
+      "charset",
+      "driver"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "namespace": [
+      "path"
+    ],
+    "config": [
+      "addfieldpath",
+      "addfieldprefix",
+      "addformpath",
+      "addformprefix",
+      "addrulepath",
+      "addruleprefix"
+    ],
+    "fields": [
+      "addfieldpath",
+      "addfieldprefix",
+      "addformpath",
+      "addformprefix",
+      "addrulepath",
+      "addruleprefix",
+      "name"
+    ],
+    "fieldset": [
+      "addfieldpath",
+      "addfieldprefix",
+      "addformpath",
+      "addformprefix",
+      "addrulepath",
+      "addruleprefix",
+      "description",
+      "label",
+      "name"
+    ],
+    "field": [
+      "*"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}
diff --git a/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_template.json b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_template.json
new file mode 100644
index 0000000..dbceb31
--- /dev/null
+++ b/administrator/components/com_jedchecker/libraries/rules/xmlmanifest/dtd_template.json
@@ -0,0 +1,119 @@
+{
+  "nodes": {
+    "extension": {
+      "name": "!",
+      "element": "?",
+      "creationDate": "=",
+      "author": "=",
+      "authorEmail": "=",
+      "authorUrl": "=",
+      "copyright": "=",
+      "version": "!",
+      "description": "=",
+      "license": "?",
+      "scriptfile": "?",
+      "install": "?",
+      "update": "?",
+      "uninstall": "?",
+      "files": "?",
+      "images": "?",
+      "css": "?",
+      "languages": "?",
+      "media": "?",
+      "positions": "=",
+      "updateservers": "?",
+      "dlid": "?",
+      "config": "?"
+    },
+    "positions": {
+      "position": "*"
+    },
+    "files": {
+      "filename": "*",
+      "files:file": "*",
+      "folder": "*"
+    },
+    "images": {
+      "filename": "*",
+      "images:file": "*",
+      "folder": "*"
+    },
+    "css": {
+      "filename": "*",
+      "css:file": "*",
+      "folder": "*"
+    },
+    "languages": {
+      "language": "*"
+    },
+    "media": {
+      "filename": "*",
+      "media:file": "*",
+      "folder": "*"
+    },
+    "install": {
+      "sql": "*"
+    },
+    "update": {
+      "sql": "*",
+      "schemas": "*"
+    },
+    "uninstall": {
+      "sql": "*"
+    },
+    "sql": {
+      "file": "*"
+    },
+    "schemas": {
+      "schemapath": "*"
+    },
+    "updateservers": {
+      "server": "*"
+    }
+  },
+  "attributes": {
+    "extension": [
+      "client",
+      "method",
+      "overwrite",
+      "type",
+      "version"
+    ],
+    "files": [
+      "folder"
+    ],
+    "images": [
+      "folder"
+    ],
+    "css": [
+      "folder"
+    ],
+    "languages": [
+      "folder"
+    ],
+    "language": [
+      "client",
+      "tag"
+    ],
+    "position": [
+      "value"
+    ],
+    "media": [
+      "destination",
+      "folder"
+    ],
+    "file": [
+      "charset",
+      "driver"
+    ],
+    "server": [
+      "name",
+      "priority",
+      "type"
+    ],
+    "dlid": [
+      "prefix",
+      "suffix"
+    ]
+  }
+}