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In the United States, 25 Hz, a once-common industrial power frequency is used on Amtrak's 25 Hz traction power system at 12 kV on the Northeast Corridor between Washington, D.C. and New York City and on the Keystone Corridor between Harrisburg, Pennsylvania and Philadelphia. SEPTA's 25 Hz traction power system uses the same 12 kV voltage on the catenary in Northeast Philadelphia. This allows for the trains to operate on both the Amtrak and SEPTA power systems. Apart from having an identical catenary voltage, the power distribution systems of Amtrak and SEPTA are very different. The Amtrak power distribution system has a 138 kV transmission network that provides power to substations which then transform the voltage to 12 kV to feed the catenary system. The SEPTA power distribution system uses a 2:1 ratio autotransformer system, with the catenary fed at 12 kV and a return feeder wire fed at 24 kV. The New York, New Haven and Hartford Railroad used an 11 kV system between New York City and New Haven, Connecticut which was converted to 12.5 kV 60 Hz in 1987.

What specification is similar for both Amtrak and Septa systems?
Answer: catenary voltage
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The AVL, created by the Valencian parliament, is in charge of dictating the official rules governing the use of Valencian, and its standard is based on the Norms of Castelló (Normes de Castelló). Currently, everyone who writes in Valencian uses this standard, except the Royal Academy of Valencian Culture (Acadèmia de Cultura Valenciana, RACV), which uses for Valencian an independent standard.

What is the AVL standard based on?
Answer: Norms of Castelló
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According to the Sixth China Census, the total population of the City of Nanjing reached 8.005 million in 2010. The statistics in 2011 estimated the total population to be 8.11 million. The birth rate was 8.86 percent and the death rate was 6.88 percent. The urban area had a population of 6.47 million people. The sex ratio of the city population was 107.31 males to 100 females.

How many people were considered to be living in the urban portion of Nanjing?
Answer:
6.47 million