- * Is this a known char from some language?
- * If \p preamble is empty and code point \p c is known to belong
- * to a supported script, true is returned and \p preamble is set
- * to the corresponding entry in the unicodesymbols file.
- * If \p preamble is not empty, a check is made whether code point
- * \p c is a known character matching the preamble entry.
+ * Test, if \p c is a supported Greek or Cyrillic letter.
+ * Return script macro name or empty string.