This form is an ancestral Wing Chun form that has been lost in the modernizations that ocured in Hong Kong. According to modern research Wing Chun was original 1 form, 4 sections. Wong Wah Bo and Leung Jan broke the single form down into the standard 3 form. The 4th section/form was typicaly integrated into the Jong form and weapon forms. The set teachs all the core footwork, as well as contains the core cycles of the Wing Chun System. Ng Chun So passed his version down to Several students. Chan family preserves the 4th form as well,as well as Lo Kwai the pork sellers decendents, suggesting that Yip Man either didnt learn it or didnt pass it down, possibly integrating it into his Weapon sets.