Euro keeps firm tone, just off two-week high of $0.8739 after better than expected German output data. - German industrial output rose 1.9 percent after a fall of 1.8 percent in November. Markets were expecting a rise of 0.2 percent. Manufacturing output rose 1.6 percent month on month. - Euro also stays near day's highs against yen at 116.85 , up 1/3 percent on day. - Dealers say euro's gains capped for now in face of offers around key resistance at $0.8730 and $0.8750. They also say U.S. equity futures point to firmer open on Wall Street, prompting investors to liquidate their euro longs especially before weekend G7 meeting. - But analysts say dollar vulnerable to concerns about corporate earnings and accounting practices.