(Bloomberg) -- An obscure financing tool used to chip away at the obligations of the world’s most indebted oil major, Petroleos Mexicanos, is now emerging as a model for other struggling borrowers. The Mexican government in July completed a $12 billion debt offering in the form of pre-capitalized securities, or P-Caps — the first time a sovereign deployed the tool. It’s a type of instrument that allows issuers, typically insurance companies, to borrow money without recording it as debt on their balance shee ...