What does Restricted Security mean in TreasuryDirect?

In 2008, I purchased $5,000 worth of I bonds through TreasuryDirect and $5,000 in paper. At the end of the year, I converted the paper to electronic. On the list of converted bonds, I had some others from much earlier years, the 2008 bond is noted with the status of "Restricted Security." None of the others, in the converted or non-converted account indicate this status. What does this mean?

Tom's response

In general, you can do anything with a converted Savings Bond in TreasuryDirect that you can do with one purchased there directly. However, removing or changing the name of a co-owner on converted Series E, EE, or I bonds, or removing or changing a beneficiary on converted Series E bonds, requires the permission of the person whose name is being removed. This can't be done online. The Restricted Security designation means that this particular bond is one that would require an offline form to change the registration in this manner.