After serializing all the words in the 'Value' columns, for the i-th word in the table x a k i whose attribute is a k (the k-th attribute), we use the attribute name a k and the word's position in that tuple to locate the word (Lebret et al., 2016).
we utilize a triple z a k i = {a k , p a k i+ , p a k i− } to represent the structure information for word x a k i , in which p a k i+ and p a k i− are the positions of x a k i counted from the beginning and end of a k , respectively.