+ * The regular "safe" macros require that the initial, passed-in string index
+ * is within bounds. They only check the index when they read more than one
+ * code unit. This is usually done with code similar to the following loop:
+ * <pre>while(i<length) {
+ * U16_NEXT(s, i, length, c);
+ * // use c
+ * }</pre>
+ *