The term FRACTION OF A MIN. can be broken down into three parts: MSEC (4 letters), SEC (3 letters), and NSEC (4 letters). MSEC stands for Milliseconds, which is a unit of time equal to one thousandth of a second. SEC stands for Seconds, which is a unit of time equal to one sixtieth of a minute. NSEC stands for Nanoseconds, which is a unit of time equal to one billionth of a second. Therefore, FRACTION OF A MIN. refers to a fraction of a minute, which can be measured in milliseconds, seconds, or nanoseconds.