Ogilvy was especially troubled by one characteristic of the subway system as it extended to Brooklyn.

NEWYORKER: Brooklyn Circle

The change is a true quantum leap, a death and re-birth, and the main characteristic of the new system is that it can handle the fluctuations, the input from the environment, that overwhelmed the old system.

FORBES: Connect

Furthermore, the main characteristic of the French political system remains - weak parliamentary rule.

BBC: RELATED BBC SITES

Andreas Schleicher, the OECD's special adviser on education, says a long-term characteristic of the UK's education system has been social division - with a polarisation between the results of rich and poor pupils.

BBC: UK weak in school fairness rankings

In doing so, they lost track of the most essential characteristic of a large-scale energy storage system: it must be cheap.

FORBES: Storage, Not Generation, is the Challenge to Renewable Energy

One key characteristic that distinguished Apple was that it had its own operating system.

FORBES: Four Events to Change Apple's Course

The water system provides drinking water for 42 million people and is a defining characteristic of the states and provinces along its borders.

NPR: Governors Meet on Access to Great Lakes

Plate tectonics, the formation of faults and the moving of the continental crust over a molten interior, is a characteristic unique to Earth and it meant that minerals evolved far beyond those on any other planet in the Solar System.

ECONOMIST: Minerals