According to http://taikyokushogi.hp.infoseek.co.jp/taikyoku.swf, this mark -|-|-|-> means 'may jump over three pieces on its way'. In this link, get the piece that starts at 20 32 out on the board and look at the forward-diagonal moves: it may move four spaces into the opponents start row, jumping over three pieces- or one, or two, jumping over one, or three, jumping over two.