GST uses the full cost accounting based on the "ceiling test." Article on different accounting methods: <a href="http://seekingalpha.com/article/118662-what-devon-s-huge-write-down-means-for-natural-gas?source=yahoo" target="_blank">http://seekingalpha.com/article/118662-what-devon-s-huge-write-down-means-for-natural-gas?source=yahoo</a>