搜尋了一下Vanguard Total Bond Market - 理財

搜尋了一下Vanguard Total Bond Market Index Fund..
竟然有以下五檔, 這是怎麼一回事, 這五檔有何差別呢?

VBMFX
Vanguard Total Bond Market Index Fund
VBTSX
Vanguard Total Bond Market Index Fund
VBMPX
Vanguard Total Bond Market Index Fund
VBTIX
Vanguard Total Bond Market Index Fund
VBTLX
Vanguard Total Bond Market Index Fund

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