Corporate Office Properties Trust, a Columbia-based real estate investment trust focused on federal government and defense contractor office buildings, reported a slight increase in funds from operations for the third quarter. FFO was $49.6 million, or 49 cents per diluted share, for the period ending Sept. 30, compared with $49.3 million and 48 cents for the same period in 2013. Revenue increased to $118.3 million for the third quarter, compared with $114.8 million for the 2013 quarter. COPT said its properties are 93 percent leased. Funds from operations is used in calculating a REIT’s financial performance because it gives a more accurate picture of cash flow.