Professional engineers of one or more kinds are available in Irvine. An engineer is a professional who applies scientific knowledge and mathematics along with innovative ideas, for solving technical problems. They work on applied sciences, and design structures, technologies, inventions and machines within the limitations of practicality, cost and safety. They act, in essence, as the link between pure sciences and the world of human applications. The word is derived from two Latin words- ingeniare ("to contrive, devise") and ingenium ("cleverness"). Specializations within the broad sector of engineering is the norm. Some of the available specializations include computer engineers, mechanical engineers, electrical engineers, civil engineers, software engineers, and so on. Each discipline has further sub specializations. Many engineers are employed by companies, or they may also do independent consulting work in Irvine. One cannot freely use the term professional engineer (PE) in the country. Before that, one has to pass two separate examinations (apart from the actual degree), along with completion of a certain number of years of experience. PEs are not only legally responsible for approval of tenders, contracts, bids and payment, they are also responsible for signing, sealing or stamping technical documentation.