*/
private static PRTokeniser getOffsetTokeniser(RandomAccessSource byteSource) throws IOException{
PRTokeniser tok = new PRTokeniser(new RandomAccessFileOrArray(byteSource));
int offset = tok.getHeaderOffset();
if (offset != 0){
RandomAccessSource offsetSource = new WindowRandomAccessSource(byteSource, offset);
tok = new PRTokeniser(new RandomAccessFileOrArray(offsetSource));
}
return tok;
}