According to the invention, a method is provided for forming an information closure of a plurality of rows in a listing stack built by a wrapper program for accessing semistructured information. This method includes removing a first row from the listing stack and computing a cross product of the fields in the first row. A step of adding this cross product to a list of accepted rows can also be part of the method. For each remaining row in the listing stack, the method includes a step of computing a selective cross product according to a plurality of steps. In one step, a result is initialized to empty. Then, for each row in the list of accepted rows, a step of determining for a first new row from the accepted row, extended with the non-empty fields of the remaining row is performed. The method can also include a step of determining a second new row from the remaining row, extended with the non-empty fields in the accepted row. Thereupon, a step of adding the two new rows to the result can be performed. Repeating the determining steps and the adding step for all rows in the list of accepted rows, and removing from the result any identical rows can provide an information closure.