Fix defaults for length units, add weight unit concordance list

src/MDConcWeights.php

@@ -0,0 +1,35 @@
+<?PHP
+/**
+ * Constains lists for categorizing misspelled weight units.
+ *
+ * @author Joshua Ramon Enslin <joshua@museum-digital.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Provides lists for categorizing misspelled sizes.
+ */
+final class MDConcWeights implements MDImporterConcordanceListInterface {
+
+    private const WEIGHTS_LIST = [
+        "cm"        => "", // Default
+        "Gramm"        => "g",
+    ];
+
+    /**
+     * Require a function for getting the concordance target.
+     *
+     * @param string $input Input string.
+     *
+     * @return string
+     */
+    public static function getConcordanceTarget(string $input):string {
+
+        if (!isset(self::WEIGHTS_LIST[$input])) {
+            throw new MDImporterMissingConcordance("Unknown weight type: " . $input);
+        }
+
+        return self::WEIGHTS_LIST[$input];
+
+    }
+}