--- /dev/null
+<?php
+
+namespace Drupal\Component\Transliteration;
+
+/**
+ * Defines an interface for classes providing transliteration.
+ *
+ * @ingroup transliteration
+ */
+interface TransliterationInterface {
+
+ /**
+ * Removes diacritics (accents) from certain letters.
+ *
+ * This only applies to certain letters: Accented Latin characters like
+ * a-with-acute-accent, in the UTF-8 character range of 0xE0 to 0xE6 and
+ * 01CD to 024F. Replacements that would result in the string changing length
+ * are excluded, as well as characters that are not accented US-ASCII letters.
+ *
+ * @param string $string
+ * The string holding diacritics.
+ *
+ * @return string
+ * $string with accented letters replaced by their unaccented equivalents.
+ */
+ public function removeDiacritics($string);
+
+ /**
+ * Transliterates text from Unicode to US-ASCII.
+ *
+ * @param string $string
+ * The string to transliterate.
+ * @param string $langcode
+ * (optional) The language code of the language the string is in. Defaults
+ * to 'en' if not provided. Warning: this can be unfiltered user input.
+ * @param string $unknown_character
+ * (optional) The character to substitute for characters in $string without
+ * transliterated equivalents. Defaults to '?'.
+ * @param int $max_length
+ * (optional) If provided, return at most this many characters, ensuring
+ * that the transliteration does not split in the middle of an input
+ * character's transliteration.
+ *
+ * @return string
+ * $string with non-US-ASCII characters transliterated to US-ASCII
+ * characters, and unknown characters replaced with $unknown_character.
+ */
+ public function transliterate($string, $langcode = 'en', $unknown_character = '?', $max_length = NULL);
+
+}