--- /dev/null
+<?php
+
+namespace Drupal\Component\Render;
+
+/**
+ * Provides an output strategy that formats HTML strings for a given context.
+ *
+ * Output strategies assist in transforming HTML strings into strings that are
+ * appropriate for a given context (e.g. plain-text), through performing the
+ * relevant formatting. No sanitization is applied.
+ */
+interface OutputStrategyInterface {
+
+ /**
+ * Transforms a given HTML string into to a context-appropriate output string.
+ *
+ * This transformation consists of performing the formatting appropriate to
+ * a given output context (e.g., plain-text email subjects, HTML attribute
+ * values).
+ *
+ * @param string|object $string
+ * An HTML string or an object with a ::__toString() magic method returning
+ * HTML markup. The source HTML markup is considered ready for output into
+ * HTML fragments and thus already properly escaped and sanitized.
+ *
+ * @return string
+ * A new string that is formatted according to the output strategy.
+ */
+ public static function renderFromHtml($string);
+
+}