Scared-
Maybe you need to make a donation to help lower the debt if you do not know what the sign means.
The Bureau of the Public Debt may accept gifts donated to the United States Government to reduce debt held by the public. Acting for the Secretary of the Treasury, Public Debt may accept a gift of:
* Money, made only on the condition that it be used to reduce debt held by the public.
* An outstanding government obligation, made only on the condition that the obligation be retired and the redemption proceeds used to reduce debt held by the public.
* Other intangible personal property made only on the condition that the property is sold and the proceeds from the sale used to reduce the public debt.