a power table saw of the type which has a generally rectangular table with front and rear end portions , a motor operatively coupled to drive a rotary cutting blade extending upwardly through a top of the table , the table saw including an elongated fence having front and rear end portions , and being configured to be laterally movable along the width of the table and be secured to the front and rear end portions of the table , front and rear releasable locking mechanisms operatively associated with the front and rear end portions of the fence for locking each end portion to the end portions of the table , and at least one positional sensor provided with each of the front and rear end portions of the fence for determining the lateral position of each end portion of the fence along the width of the table .