diff --git a/docs/src/content/docs/en/plugins/manifest.mdx b/docs/src/content/docs/en/plugins/manifest.mdx
index ecf315c1..192a824f 100644
--- a/docs/src/content/docs/en/plugins/manifest.mdx
+++ b/docs/src/content/docs/en/plugins/manifest.mdx
@@ -50,14 +50,28 @@ The URL to the project homepage.
 
 ### license
 
+**Default:** `"UNLICENSED"`
+
 Specify a license for your plugin so that people know how they are permitted to
 use it, and any restrictions you're placing on it.
 
 ### private
 
+**Default:** `false`
+
 Whether or not to publish the plugin in public directories. If set to `true`,
 directories should refuse to publish the plugin.
 
+### submodule
+
+**Default:** `false`
+
+Indicates whether the plugin is part of a monorepo (a single Git repository
+containing multiple plugins). If `true`, the plugin shares its repository with
+other plugins. In this case, releases should be tagged using the format
+`<plugin-name>@<version>` (eg. `acme/hello-world@1.0.0`) to ensure proper
+version indexing by plugin repositories.
+
 ### keywords
 
 Array of strings to help your plugin get discovered when listed in repositories.
diff --git a/modules/Plugins/Manifest/Manifest.php b/modules/Plugins/Manifest/Manifest.php
index 59c65ab3..6c098d6c 100644
--- a/modules/Plugins/Manifest/Manifest.php
+++ b/modules/Plugins/Manifest/Manifest.php
@@ -15,6 +15,7 @@ use CodeIgniter\HTTP\URI;
  * @property ?URI $homepage
  * @property ?string $license
  * @property bool $private
+ * @property bool $submodule
  * @property list<string> $keywords
  * @property ?string $minCastopodVersion
  * @property list<string> $hooks
@@ -31,6 +32,7 @@ class Manifest extends ManifestObject
         'homepage'           => 'permit_empty|valid_url_strict',
         'license'            => 'permit_empty|string',
         'private'            => 'permit_empty|is_boolean',
+        'submodule'          => 'permit_empty|is_boolean',
         'keywords.*'         => 'permit_empty',
         'minCastopodVersion' => 'permit_empty|regex_match[/^(0|[1-9]\d*)\.(0|[1-9]\d*)(\.(0|[1-9]\d*))?(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/]',
         'hooks.*'            => 'permit_empty|in_list[rssBeforeChannel,rssAfterChannel,rssBeforeItem,rssAfterItem,siteHead]',
@@ -62,6 +64,8 @@ class Manifest extends ManifestObject
 
     protected bool $private = false;
 
+    protected bool $submodule = false;
+
     /**
      * @var list<string>
      */
diff --git a/modules/Plugins/Manifest/manifest.schema.json b/modules/Plugins/Manifest/manifest.schema.json
index 71c71980..9ace64aa 100644
--- a/modules/Plugins/Manifest/manifest.schema.json
+++ b/modules/Plugins/Manifest/manifest.schema.json
@@ -59,7 +59,13 @@
     },
     "private": {
       "type": "boolean",
-      "description": "If set to true, then repositories should refuse to publish it."
+      "description": "If set to true, then repositories should refuse to publish it.",
+      "default": false
+    },
+    "submodule": {
+      "type": "boolean",
+      "description": "Set to `true` if the plugin is part of a monorepo (i.e., in the same Git repository as other plugins). Releases should be tagged as `<plugin-name>@<version>` to ensure proper version indexing by plugin repositories.",
+      "default": false
     },
     "keywords": {
       "description": "This helps people discover your plugin as it's listed in repositories",