We can't afford for the performance to run on for more than the specifiedtime.
It makessure that the fieldnameargument is not empty, and that the fieldspecified there is an actualexistingfield in the class which declares the methoddecorated with this attribute.
Your computerhibernatesafter it has been idle for the specifiedamount of time. — Microsoft Corp, UseHibernate and Standby to ConserveBatteries (2001)