The General Bond Fund tracks the performance of the underlying index, which in turn tracks the entire bond market.
Investing in a general bond fund gives investors the same exposure to the bond market as more traditional bond investments, but offers a very liquid option in a traditionally very illiquid sector.
For general bond funds to work, they must have the same maturity as the bonds in the underlying index.
One of the most popular general bond funds offered by Vanguard is called the Vanguard Total Bond Market Index Fund.