(2) Operating margin is a non-GAAP financial measure and is discussed under "Targa Resources Partners - Non-GAAP Financial Measures."
(3) Adjusted EBITDA is net income before: interest, income taxes, depreciation and amortization, gains or losses on debt repurchases and debt redemptions, early debt extinguishments and asset disposals, non-cash risk management activities related to derivative instruments and changes in the fair value of the Badlands acquisition contingent consideration. This is a non-GAAP financial measure and is discussed under "Targa Resources Partners - Non-GAAP Financial Measures."
(4) Distributable cash flow is income attributable to Targa Resources Partners LP plus depreciation and amortization, deferred taxes and amortization of debt issue costs included in interest expense, adjusted for non-cash losses (gains) on mark-to-market derivative contracts, debt repurchases, debt redemptions, early debt extinguishments, asset disposals, less maintenance capital expenditures (net of any reimbursements of project costs) and changes in the fair value of the Badlands acquisition contingent consideration. This is a non-GAAP financial measure and is discussed under "Targa Resources Partners - Non-GAAP Financial Measures."
(5) Plant natural gas inlet represents the volume of natural gas passing through the meter located at the inlet of a natural gas processing plant.(6) Plant natural gas inlet volumes include producer take-in-kind volumes, while natural gas sales exclude producer take-in-kind volumes. Targa Resources Partners – Review of Consolidated Third Quarter Results Three Months Ended September 30, 2013 Compared to Three Months Ended September 30, 2012 The increase in revenues primarily reflects higher commodity sales volumes ($77.4 million), higher realized prices on natural gas and condensate ($61.7 million), and higher fee-based and other revenues ($34.4 million). The increase in consolidated gross margin was driven by increased volumes and higher natural gas prices in our Field Gathering and Processing segment and higher fractionation fees and increased exports activities in our Logistics and Marketing division. These favorable factors were partially offset by lower NGL prices in our Coastal Gathering and Processing segment. Higher operating expenses were driven by system expansions related to new operations in Field Gathering and Processing and of new growth projects in Logistics, costs associated with our Badlands growth and other higher labor and maintenance costs. See "Targa Resources Partners – Review of Segment Performance" for additional information regarding changes in the components of gross and operating margin on a disaggregated basis.