diff --git a/src/Impact/Type.php b/src/Impact/Type.php
index 8c96b05e..42390d95 100644
--- a/src/Impact/Type.php
+++ b/src/Impact/Type.php
@@ -85,6 +85,69 @@ class Type
         self::IMPACT_EPT    => 'ept',
     ];
 
+    private static array $impact_categorization = [
+        'Acidification' => [
+            'ap',
+        ], 'Climate change' => [
+            'gwp',
+        ], 'Ecotoxicity, freshwater' => [
+            'ctue',
+        ], 'EF-particulate matter' => [
+            'pm',
+        ], 'Eutrophication, freshwater' => [
+            'epf',
+        ], 'Eutrophication, marine' => [
+            'epm',
+        ], 'Eutrophication, terrestrial' => [
+            'ept',
+        ], 'Human toxicity, cancer' => [
+            'ctuh_c',
+        ], 'Human toxicity, non-cancer' => [
+            'ctuh_nc',
+        ], 'Ionising radiation' => [
+            'ir',
+        ], 'Land use' => [
+            'lu',
+        ], 'Ozone depletion' => [
+            'odp',
+        ], 'Photochemical ozone formation' => [
+            'pocp',
+        ], 'Resource depletion, fossils' => [
+            'adpf',
+        ], 'Resource depletion, minerals and metals' => [
+            'adp',
+        ], 'Water use' => [
+            'wu',
+        ],
+    ];
+
+    /**
+     * Impact weight factor
+     * Sum must be equal to 100%
+     * @see https://eplca.jrc.ec.europa.eu/permalink/EF3_1/Normalisation_Weighting_Factors_EF_3.1.xlsx
+     * @see Source: Sala S, Cerutti AK, Pant R. (2018). Development of a weighting approach for Environmental Footprint. European Commission, Joint Research Centre, Publication Office of the European Union, Luxembourg. ISBN 978-92-79-68041-0.
+     *
+     * @var array<string, float>
+     */
+    private static array $category_weight_percentage = [
+        'Acidification' =>	                            6.20,
+        'Climate change' =>	                            21.06,
+        'Ecotoxicity, freshwater' =>	                1.92,
+        'EF-particulate matter' =>	                    8.96,
+        'Eutrophication, freshwater' =>	                2.80,
+        'Eutrophication, marine' =>	                    2.96,
+        'Eutrophication, terrestrial' =>	            3.71,
+        'Human toxicity, cancer' =>	                    2.13,
+        'Human toxicity, non-cancer' =>	                1.84,
+        'Ionising radiation' =>	                        5.01,
+        'Land use' =>	                                7.94,
+        'Ozone depletion' =>	                        6.31,
+        'Photochemical ozone formation' =>	            4.78,
+        'Resource depletion, fossils' =>	            8.32,
+        'Resource depletion, minerals and metals' =>	7.55,
+        'Water use' =>	                                8.51,
+    ];
+
     /**
      * Unit of impact criterias
      *
@@ -101,7 +164,7 @@ class Type
         'lu'     => null,
         'odp'    => ['g', 'CFC-11 eq'],
         'pm'     => null,
-        'pocp'   => ['g', 'U235 eq'],
+        'pocp'   => ['g', 'NMVOC eq'],
         'wu'     => ['m³', ''],
         'mips'   => ['g', ''],
         'adpe'   => ['g', 'SB eq'],
@@ -401,4 +464,5 @@ public static function getCriteriaInfoLink(string $impact_type): string
 
         return '';
     }
+
 }
diff --git a/tests/units/Impact/TypeTest.php b/tests/units/Impact/TypeTest.php
new file mode 100644
index 00000000..cf7eb9a2
--- /dev/null
+++ b/tests/units/Impact/TypeTest.php
@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * -------------------------------------------------------------------------
+ * Carbon plugin for GLPI
+ *
+ * @copyright Copyright (C) 2024-2025 Teclib' and contributors.
+ * @copyright Copyright (C) 2024 by the carbon plugin team.
+ * @license   https://www.gnu.org/licenses/gpl-3.0.txt GPLv3+
+ * @link      https://github.com/pluginsGLPI/carbon
+ *
+ * -------------------------------------------------------------------------
+ *
+ * LICENSE
+ *
+ * This file is part of Carbon plugin for GLPI.
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * -------------------------------------------------------------------------
+ */
+
+namespace GlpiPlugin\Carbon\Impact\Tests;
+
+use GlpiPlugin\Carbon\Impact\Type;
+use GlpiPlugin\Carbon\Tests\DbTestCase;
+use PHPUnit\Framework\Attributes\CoversClass;
+use ReflectionClass;
+
+#[CoversClass(Type::class)]
+class TypeTest extends DbTestCase
+{
+    public function test_category_weight_percentage_sum_equals_100_percent(): void
+    {
+        $reflection = new ReflectionClass(Type::class);
+        $property = $reflection->getProperty('category_weight_percentage');
+        // $property->setAccessible(true);
+        $weights = $property->getValue();
+
+        $sum = array_sum($weights);
+
+        $this->assertEquals(100.0, $sum);
+    }
+}