Methods, apparatus, techniques and computer program products for joint reduction of crosstalk in a synchronized, time division duplexed DSL systems use sequential removal of NEXT interference followed by removal of FEXT interference from a received DSL signal. The system also may include a heat spreader disposed along the plurality of memory circuits. When an arbitrary Wordbook n registered in the wordbook database is selected and called up, each item name registered in the selected wordbook is associated with a color mark according to the highlighter existence data for each color and displayed in a registered wordlist screen. The heating element has at least one ionic current detection electrode made of an electrically conducting ceramic material.