BILL OBLIGATORY. An instrument in common use and too well known to be misunderstood. It is a bond without condition, sometimes called a single bill, and differs in nothing from a promissory note, but the seal which is affixed to it. 2 Serg. & Rawle, 115. See Read's Pleaders' Assistant, 256, for a declaration setting forth such a bill. Also West's Symboleography, s. 100, 101, for the forms both with and without a penalty.