diff --git a/src/main/resources/org/eolang/lints/metas/unknown-metas.xsl b/src/main/resources/org/eolang/lints/metas/unknown-metas.xsl
new file mode 100644
index 0000000..8d87968
--- /dev/null
+++ b/src/main/resources/org/eolang/lints/metas/unknown-metas.xsl
@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+The MIT License (MIT)
+
+Copyright (c) 2016-2024 Objectionary.com
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+-->
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" id="unknown-metas" version="2.0">
+  <xsl:output encoding="UTF-8" method="xml"/>
+  <xsl:template match="/">
+    <defects>
+      <xsl:for-each select="/program/metas/meta">
+        <xsl:variable name="meta-head" select="head"/>
+        <xsl:variable name="predefined" select="('package', 'alias', 'version', 'tests', 'rt', 'architect', 'home', 'unlint', 'probe')"/>
+        <xsl:if test="not($meta-head = $predefined)">
+          <xsl:element name="defect">
+            <xsl:attribute name="line">
+              <xsl:value-of select="if (@line) then @line else '0'"/>
+            </xsl:attribute>
+            <xsl:attribute name="severity">
+              <xsl:text>warning</xsl:text>
+            </xsl:attribute>
+            <xsl:text>Unknown meta used "</xsl:text>
+            <xsl:value-of select="$meta-head"/>
+            <xsl:text>"</xsl:text>
+          </xsl:element>
+        </xsl:if>
+      </xsl:for-each>
+    </defects>
+  </xsl:template>
+</xsl:stylesheet>
diff --git a/src/main/resources/org/eolang/motives/metas/unknown-metas.md b/src/main/resources/org/eolang/motives/metas/unknown-metas.md
new file mode 100644
index 0000000..917c6a1
--- /dev/null
+++ b/src/main/resources/org/eolang/motives/metas/unknown-metas.md
@@ -0,0 +1,36 @@
+# Unknown Metas
+
+The following metas are supported:
+
+* `+package`
+* `+alias`
+* `+version`
+* `+tests`
+* `+rt`
+* `+architect`
+* `+home`
+* `+unlint`
+* `+probe`
+
+Incorrect:
+
+```eo
++foo
++bar
+
+[] > foo
+```
+
+Correct:
+
+```eo
++package com.test
++alias foo
++version 0.0.0
++architect yegor256@gmail.com
++rt jvm
++home https://earth.com
++unlint unsorted-metas
+
+[] > foo
+```
diff --git a/src/test/resources/org/eolang/lints/eo-packs/catches-unknown-metas.yaml b/src/test/resources/org/eolang/lints/eo-packs/catches-unknown-metas.yaml
new file mode 100644
index 0000000..f8c9458
--- /dev/null
+++ b/src/test/resources/org/eolang/lints/eo-packs/catches-unknown-metas.yaml
@@ -0,0 +1,43 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2016-2024 Objectionary.com
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+---
+xsls:
+  - /org/eolang/lints/metas/unknown-metas.xsl
+tests:
+  - /defects[count(defect[@severity='warning'])=3]
+  - /defects/defect[@line='1']
+  - /defects/defect[@line='2']
+  - /defects/defect[@line='3']
+eo: |
+  +foo
+  +bar
+  +bad
+  +package test
+  +alias foo
+  +version 0.0.0
+  +architect yegor256@gmail.com
+  +rt node
+  +home https://earth.com
+  +unlint test
+  +probe
+
+  [] > foo