TSP voting privileges

The Federal Employees’ Retirement System Act of 1986 (and the accompanying conference report), which established the TSP, prohibited the Board (and TSP participants) from voting proxies in the firms whose stocks make up the TSP stock index funds.

Barclays, nowever, (as the asset management contractor) is directed by the Board to “Vote all proxies and address all corporate actions in a manner which will result in maximum financial benefits to TSP participants and in accordance with fiduciary responsibilities.” So how does Barclays decide what will result in the max financial benefits for TSP investors? Is there a record of their votes anywhere?