Government-issued securities such as War Stock are often referred to in the UK as Gilts. These enable a sovereign state to borrow money - thus the term "Sovereign Bonds" - in exchange for a guarantee on the capital and a competitive return.
US and Western European issues offer a low-risk environment, while areas such as Latin America or Russia offer higher returns but an element of risk in defaulting. Most of these securities mature at par (100 percent of nominal value) but can be purchased above or below par, depending upon the interest rate (V's) and the securities return (coupon). Taking this into consideration, the true yield if held to maturity can be calculated.