Natural gas and electricity provider PG&E Corp. of Northern California recently declared its intention to file for bankruptcy protection under the U.S. bankruptcy code, Chapter 11. If that happens, the valuation of the filing may approach the size of the bankruptcy of the utility company in 2001 on some $36 billion in assets, as seems unavoidable. There are two main flavors of U.S. bankruptcy protection: Chapter 11, which preserves the assets of the company while reorganizing