You are the CFO for Burton's Drill Rigs, a provider of oilfield services. It reports earnings on a calendar year and it takes you 90 days to issue your annual report. In 2015, Linn Energy was Burton's largest customer and generated 47% of its revenue. On 2/1/16, Linn Energy field for bankruptcy. As a CPA following GAAP, summarize at least two disclosure notes regarding this customer in your 2015 annual report?