Extend MDMeasurement with surrounding enums to cover measurements of

objects

src/MDMeasurementUnitInterface.php

@@ -0,0 +1,21 @@
+<?PHP
+/**
+ * Describes an interface for a measurement units.
+ *
+ * @author Joshua Ramon Enslin <joshua@museum-digital.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Describes an interface for a measurement units.
+ */
+interface MDMeasurementUnitInterface {
+    /**
+     * Returns the measurement calculated down to the base unit (e.g. mm for lengths).
+     *
+     * @param float $value Measurement value.
+     *
+     * @return float
+     */
+    public function convertToBaseUnit(float $value):float;
+}