diff --git a/lib/classes/deprecated.php b/lib/classes/deprecated.php
index deb278abe94..452f7844f2e 100644
--- a/lib/classes/deprecated.php
+++ b/lib/classes/deprecated.php
@@ -34,20 +34,25 @@ class deprecated {
      *
      * Note: The mere presence of the attribute does not do anything. It must be checked by some part of the code.
      *
-     * @param mixed $descriptor A brief descriptor of the thing that was deprecated.
+     * @param null|string $replacement Any replacement for the deprecated thing
      * @param null|string $since When it was deprecated
      * @param null|string $reason Why it was deprecated
-     * @param null|string $replacement Any replacement for the deprecated thing
      * @param null|string $mdl Link to the Moodle Tracker issue for more information
+     * @param bool $final Whether this is a final deprecation
+     * @param bool $emit Whether to emit a deprecation warning
      */
     public function __construct(
-        public readonly mixed $descriptor,
+        public readonly ?string $replacement,
         public readonly ?string $since = null,
         public readonly ?string $reason = null,
-        public readonly ?string $replacement = null,
         public readonly ?string $mdl = null,
         public readonly bool $final = false,
         public readonly bool $emit = true,
     ) {
+        if ($replacement === null && $reason === null && $mdl === null) {
+            throw new \coding_exception(
+                'A deprecated item which is not deprecated must provide a reason, or an issue number.',
+            );
+        }
     }
 }
diff --git a/lib/classes/deprecated_with_reference.php b/lib/classes/deprecated_with_reference.php
new file mode 100644
index 00000000000..82b1621d7dc
--- /dev/null
+++ b/lib/classes/deprecated_with_reference.php
@@ -0,0 +1,58 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace core;
+
+/**
+ * Attribute to describe a deprecated item.
+ *
+ * @package    core
+ * @copyright  2023 Andrew Lyons <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class deprecated_with_reference extends deprecated {
+    /**
+     * A deprecated item which also includes a reference to the owning feature.
+     *
+     * This attribute is not expected to be used more generally. It is an internal feature.
+     *
+     * @param string $owner The code which owns the usage
+     * @param null|string $replacement Any replacement for the deprecated thing
+     * @param null|string $since When it was deprecated
+     * @param null|string $reason Why it was deprecated
+     * @param null|string $mdl Link to the Moodle Tracker issue for more information
+     * @param bool $final Whether this is a final deprecation
+     * @param bool $emit Whether to emit a deprecation warning
+     */
+    public function __construct(
+        public readonly string $owner,
+        ?string $replacement,
+        ?string $since,
+        ?string $reason,
+        ?string $mdl,
+        bool $final,
+        bool $emit,
+    ) {
+        parent::__construct(
+            replacement: $replacement,
+            since: $since,
+            reason: $reason,
+            mdl: $mdl,
+            final: $final,
+            emit: $emit,
+        );
+    }
+}
diff --git a/lib/classes/deprecation.php b/lib/classes/deprecation.php
index b71fd502d9b..eb8fa7e416f 100644
--- a/lib/classes/deprecation.php
+++ b/lib/classes/deprecation.php
@@ -49,10 +49,7 @@ class deprecation {
 
             if (function_exists($reference)) {
                 // The reference looks to be a global function.
-                $ref = new \ReflectionFunction($reference);
-                if ($attributes = $ref->getAttributes(deprecated::class)) {
-                    return $attributes[0]->newInstance();
-                }
+                return self::get_attribute(new \ReflectionFunction($reference), $reference);
             }
 
             return null;
@@ -85,6 +82,32 @@ class deprecation {
         }
     }
 
+    /**
+     * Get a deprecation attribute from a reflector.
+     *
+     * @param \Reflector $ref The reflector
+     * @param string $owner A descriptor of the owner of the thing that is deprecated
+     * @return null|deprecated_with_reference
+     */
+    protected static function get_attribute(
+        \Reflector $ref,
+        string $owner,
+    ): ?deprecated_with_reference {
+        if ($attributes = $ref->getAttributes(deprecated::class)) {
+            $attribute = $attributes[0]->newInstance();
+            return new deprecated_with_reference(
+                owner: $owner,
+                replacement: $attribute->replacement,
+                since: $attribute->since,
+                reason: $attribute->reason,
+                mdl: $attribute->mdl,
+                final: $attribute->final,
+                emit: $attribute->emit,
+            );
+        }
+        return null;
+    }
+
     /**
      * Check if a reference is deprecated.
      *
@@ -107,47 +130,44 @@ class deprecation {
     }
 
     /**
-     * Fetch a deprecation attribute from a reflected object.
+     * Fetch a referenced deprecation attribute from a reflected object.
      *
      * @param \ReflectionClass $rc The reflected object
      * @param null|string $name The name of the thing to check for deprecation
-     * @return null|deprecated
+     * @return null|deprecated_with_reference
      */
     protected static function from_reflected_object(
         \ReflectionClass $rc,
         ?string $name,
-    ): ?deprecated {
+    ): ?deprecated_with_reference {
         if ($name === null) {
             // No name specified. This may be a deprecated class.
-            if ($attributes = $rc->getAttributes(deprecated::class)) {
-                return $attributes[0]->newInstance();
-            }
-            return null;
+            return self::get_attribute($rc, $rc->name);
         }
 
         if ($rc->hasConstant($name)) {
             // This class has a constant with the specified name.
             // Note: This also applies to enums.
-            $ref = $rc->getReflectionConstant($name);
-            if ($attributes = $ref->getAttributes(deprecated::class)) {
-                return $attributes[0]->newInstance();
-            }
+            return self::get_attribute(
+                $rc->getReflectionConstant($name),
+                "{$rc->name}::{$name}",
+            );
         }
 
         if ($rc->hasMethod($name)) {
             // This class has a method with the specified name.
-            $ref = $rc->getMethod($name);
-            if ($attributes = $ref->getAttributes(deprecated::class)) {
-                return $attributes[0]->newInstance();
-            }
+            return self::get_attribute(
+                $rc->getMethod($name),
+                "{$rc->name}::{$name}",
+            );
         }
 
         if ($rc->hasProperty($name)) {
             // This class has a property with the specified name.
-            $ref = $rc->getProperty($name);
-            if ($attributes = $ref->getAttributes(deprecated::class)) {
-                return $attributes[0]->newInstance();
-            }
+            return self::get_attribute(
+                $rc->getProperty($name),
+                "{$rc->name}::{$name}",
+            );
         }
 
         return null;
@@ -157,10 +177,19 @@ class deprecation {
      * Get a string describing the deprecation.
      *
      * @param deprecated $attribute
+     * @param string $owner
      * @return string
      */
-    public static function get_deprecation_string(deprecated $attribute): string {
-        $output = "Deprecation: {$attribute->descriptor} has been deprecated";
+    public static function get_deprecation_string(
+        deprecated $attribute,
+    ): string {
+        $output = "Deprecation:";
+
+        if ($attribute instanceof deprecated_with_reference) {
+            $output .= " {$attribute->owner}";
+        }
+        $output .= " has been deprecated";
+
         if ($attribute->since) {
             $output .= " since {$attribute->since}";
         }
@@ -187,7 +216,9 @@ class deprecation {
      *
      * @param deprecated $attribute
      */
-    public static function emit_deprecation_notice(deprecated $attribute): void {
+    protected static function emit_deprecation_notice(
+        deprecated $attribute,
+    ): void {
         if (!$attribute->emit) {
             return;
         }
diff --git a/lib/classes/param.php b/lib/classes/param.php
index 359ffc37b29..e6cba152b07 100644
--- a/lib/classes/param.php
+++ b/lib/classes/param.php
@@ -222,9 +222,9 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::CLEAN',
+        replacement: 'a more specific type of parameter',
         since: '2.0',
-        reason: 'Please use a more specific type of parameter',
+        reason: 'The CLEAN param type is too generic to perform satisfactory validation',
         emit: false,
     )]
     case CLEAN = 'clean';
@@ -234,7 +234,7 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::INTEGER',
+        replacement: 'param::INT',
         since: '2.0',
         reason: 'Alias for INT',
         final: true,
@@ -246,7 +246,7 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::NUMBER',
+        replacement: 'param::FLOAT',
         since: '2.0',
         reason: 'Alias for FLOAT',
         final: true,
@@ -259,7 +259,7 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::ACTION',
+        replacement: 'param::ALPHANUMEXT',
         since: '2.0',
         reason: 'Alias for PARAM_ALPHANUMEXT',
         final: true,
@@ -272,7 +272,7 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::FORMAT',
+        replacement: 'param::ALPHANUMEXT',
         since: '2.0',
         reason: 'Alias for PARAM_ALPHANUMEXT',
         final: true,
@@ -284,7 +284,7 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::MULTILANG',
+        replacement: 'param::TEXT',
         since: '2.0',
         reason: 'Alias for PARAM_TEXT',
         final: true,
@@ -303,7 +303,7 @@ enum param: string {
      * @deprecated since 2.0
      */
     #[deprecated(
-        'param::CLEANFILE',
+        replacement: 'param::FILE',
         since: '2.0',
         reason: 'Alias for PARAM_FILE',
     )]
diff --git a/lib/tests/deprecation_test.php b/lib/tests/deprecation_test.php
index 12a0dd52bd9..efa1fd8e48d 100644
--- a/lib/tests/deprecation_test.php
+++ b/lib/tests/deprecation_test.php
@@ -24,6 +24,7 @@ namespace core;
  * @copyright  2024 Andrew Lyons <andrew@nicols.co.uk>
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  * @covers \core\deprecated
+ * @covers \core\deprecated_with_reference
  * @covers \core\deprecation
  */
 class deprecation_test extends \advanced_testcase {
@@ -40,11 +41,13 @@ class deprecation_test extends \advanced_testcase {
         }
 
         $attribute = new deprecated(
-            'Test description',
             ...$args,
+            replacement: 'Test replacement',
         );
 
-        deprecation::emit_deprecation_notice($attribute);
+        $rc = new \ReflectionClass(deprecation::class);
+        $method = $rc->getMethod('emit_deprecation_notice');
+        $method->invoke(null, $attribute);
 
         if ($expectdebugging) {
             $this->assertdebuggingcalledcount(1);
@@ -92,19 +95,20 @@ class deprecation_test extends \advanced_testcase {
      * @dataProvider get_deprecation_string_provider
      */
     public function test_get_deprecation_string(
-        string $descriptor,
+        ?string $replacement,
         ?string $since,
         ?string $reason,
-        ?string $replacement,
         ?string $mdl,
         string $expected,
     ): void {
-        $attribute = new deprecated(
-            descriptor: $descriptor,
+        $attribute = new deprecated_with_reference(
+            owner: 'Test description',
+            replacement: $replacement,
             since: $since,
             reason: $reason,
-            replacement: $replacement,
             mdl: $mdl,
+            final: false,
+            emit: true,
         );
 
         $this->assertEquals(
@@ -112,63 +116,81 @@ class deprecation_test extends \advanced_testcase {
             deprecation::get_deprecation_string($attribute),
         );
 
-        deprecation::emit_deprecation_notice($attribute);
+        $rc = new \ReflectionClass(deprecation::class);
+        $method = $rc->getMethod('emit_deprecation_notice');
+        $method->invoke(null, $attribute);
+
         $this->assertDebuggingCalled($expected);
     }
 
     public static function get_deprecation_string_provider(): array {
         return [
             [
-                'Test description',
-                null,
-                null,
-                null,
-                null,
-                'Deprecation: Test description has been deprecated.',
-            ],
-            [
-                'Test description',
-                '4.1',
-                null,
-                null,
-                null,
-                'Deprecation: Test description has been deprecated since 4.1.',
-            ],
-            [
-                'Test description',
-                null,
-                'Test reason',
-                null,
-                null,
-                'Deprecation: Test description has been deprecated. Test reason.',
-            ],
-            [
-                'Test description',
-                null,
-                null,
                 'Test replacement',
                 null,
+                null,
+                null,
                 'Deprecation: Test description has been deprecated. Use Test replacement instead.',
             ],
             [
-                'Test description',
+                'Test replacement',
+                '4.1',
                 null,
                 null,
+                'Deprecation: Test description has been deprecated since 4.1. Use Test replacement instead.',
+            ],
+            [
+                'Test replacement',
+                null,
+                'Test reason',
+                null,
+                'Deprecation: Test description has been deprecated. Test reason. Use Test replacement instead.',
+            ],
+            [
+                'Test replacement',
+                null,
+                null,
+                null,
+                'Deprecation: Test description has been deprecated. Use Test replacement instead.',
+            ],
+            [
+                'Test replacement',
+                null,
                 null,
                 'https://docs.moodle.org/311/en/Deprecated',
-                'Deprecation: Test description has been deprecated. See https://docs.moodle.org/311/en/Deprecated for more information.',
+                'Deprecation: Test description has been deprecated. Use Test replacement instead. See https://docs.moodle.org/311/en/Deprecated for more information.',
             ],
             [
-                'Test description',
+                'Test replacement',
                 '4.1',
                 'Test reason',
-                'Test replacement',
                 'https://docs.moodle.org/311/en/Deprecated',
                 'Deprecation: Test description has been deprecated since 4.1. Test reason. Use Test replacement instead. See https://docs.moodle.org/311/en/Deprecated for more information.',
             ],
+            [
+                null,
+                null,
+                'Test reason',
+                null,
+                'Deprecation: Test description has been deprecated. Test reason.',
+            ],
+            [
+                null,
+                null,
+                null,
+                'MDL-80677',
+                'Deprecation: Test description has been deprecated. See MDL-80677 for more information.',
+            ],
         ];
     }
 
+    public function test_deprecated_without_replacement(): void {
+        $this->expectException(\coding_exception::class);
+        new deprecated(
+            replacement: null,
+        );
+    }
+
     /**
      * @dataProvider from_provider
      */
@@ -230,6 +252,9 @@ class deprecation_test extends \advanced_testcase {
             ['non_existent_class', false],
             [['non_existent_class'], false],
 
+            // Non-existent feature in an existent class.
+            [[\core\fixtures\not_deprecated_class::class, 'no_such_method'], false],
+
             // Not-deprecated class.
             [\core\fixtures\not_deprecated_class::class, false],
 
diff --git a/lib/tests/fixtures/deprecated_fixtures.php b/lib/tests/fixtures/deprecated_fixtures.php
index a5f8990f474..b8bf75a2cb0 100644
--- a/lib/tests/fixtures/deprecated_fixtures.php
+++ b/lib/tests/fixtures/deprecated_fixtures.php
@@ -26,27 +26,32 @@ use core\deprecated;
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-#[deprecated('Deprecated class')]
+#[deprecated('not_deprecated_class')]
 class deprecated_class {
     protected string $notdeprecatedproperty = 'Not deprecated property';
 
-    #[deprecated('Deprecated property')]
+    #[deprecated('$this->notdeprecatedproperty')]
     protected string $deprecatedproperty = 'Deprecated property';
 
     const NOT_DEPRECATED_CONST = 'Not deprecated const';
 
-    #[deprecated('Deprecated const')]
+    #[deprecated('not_deprecated_class::NEW_CONSTANT')]
     const DEPRECATED_CONST = 'Deprecated const';
 
-    public function not_deprecated_method() {}
+    public function not_deprecated_method() {
+    }
 
-    #[deprecated('Deprecated method')]
-    public function deprecated_method() {}
+    #[deprecated(replacement: null, mdl: 'MDL-80677')]
+    public function deprecated_method() {
+    }
 }
 
-class not_deprecated_class {}
+class not_deprecated_class {
+}
 
-function not_deprecated_function() {}
+function not_deprecated_function() {
+}
 
-#[deprecated('Deprecated function')]
-function deprecated_function() {}
+#[deprecated('not_deprecated_class::not_deprecated_method()')]
+function deprecated_function() {
+}