The iterator's current position is set to the first boundary. The character index of the first text boundary. The iterator's current position is set to the last boundary. The character index of the last text boundary. A value of 0 does nothing.
Negative values move to previous boundaries and positive values move to later boundaries.
The index of the nth boundary from the current position. The character index of the next text boundary or DONE if all boundaries have been returned. The character index of the previous text boundary or DONE if all boundaries have been returned. Return the first boundary following the specified offset. The value returned is always greater than the offset or the value BreakIterator.