This standard specifies the minimum unobstructed space provided below the starting point of the aircraft's main jack to accommodate a tripod jack and to ensure adequate clearance between the jack and adjacent aircraft structures. This standard does not define all jack space dimensions. In critical space situations, this standard is only used as a reference for design. The final critical space should be determined based on the actual size of the jack used.
ISO 1464:1985 Referenced Document
ISO 43 Aircraft - Jacking pads*， 2016-11-01 Update