This recommended practice establishes procedures for determining seat location relative to basic datum points or planes on agricultural and construction machines. Alternate procedures are specified including an H-Point@ determined with the device specified in SAE J826b and a Seat Index Point (SIP) procedure to provide for use of simplified device. When a specific procedure is not designated@ the H-Point and SIP are equivalent and can be used interchangeably within normal measurement tolerances. Purpose- The purpose of this SAE Recommended Practice is to provide uniform methods for defining the location of the operator seat relative to other components on the machine. The resulting dimensions are intended to aid during the design phase of the machine and to determine compliance with applicable standards or regulations.