31 CFR §363.202

1. (a)Purchase.
   1. (1)Advance purchase. You may purchase any marketable Treasury security that is available for purchase through the TreasuryDirect ® website. One day each week, marketable securities that are scheduled for auction within 8 weeks will be made available on the TreasuryDirect website for scheduling an advance purchase, and are the only marketable securities that you can schedule for advance purchase.
   2. (2)Purchases scheduled prior to May 15, 2010, with an effective issue date on or after May 15, 2010.
      1. (i)Any marketable security purchase scheduled prior to May 15, 2010, and with an effective issue date of May 15, 2010, through July 9, 2010, will be treated as a new purchase, even if the transaction would have been treated as a reinvestment under the rules in effect prior to May 15, 2010.
      2. (ii)Any marketable security purchase scheduled prior to May 15, 2010, with an effective issue date after July 9, 2010, will be canceled.
2. (b)Hold. You may transfer into the system and maintain in your TreasuryDirect account any eligible marketable book-entry Treasury bill, note, or bond.