What is a "technology center"?

The United States Patent and Trademark Office has different technology centers responsible for handling different types of inventions.  As taken from the U.S.P.T.O. website:

Technology Center 1600 provides examination for patent applications including Biotechnology and Organic fields.
Technology Center 1700 provides examination for patent applications including Chemical and Materials Engineering fields.
Technology Center 2100 provides examination for patent applications including Computer Architecture Software and Information Security.
Technology Center 2400 provides examination for patent application including Computer Networks, Multiplex, Cable and Cryptography/Security.
Technology Center 2600 provides examination for patent applications including Communications.
Technology Center 2800 provides examination for patent applications including Semiconductors, Electrical and Optical Systems and Components.
Technology Center 2900 provides examination for patent applications including Designs.
Technology Center 3600 provides examination for patent applications including Transportation, Electronic Commerce, Construction, Agriculture, Licensing and Review.
Technology Center 3700 provides examination for patent applications including Mechanical Engineering, Manufacturing and Products.