REFERENCE Subcommand (SPCHART command)

REFERENCE controls which vertical reference lines are displayed on a process capability chart. It only applies when the chart specification is /CPCHART.

SL. Vertical reference lines are displayed at the specified values of LSL and USL as well as at the value of TARGET if specified. This is the default.

SIGMAS. Vertical reference lines are displayed at the process mean and at a specified number of capability sigmas above and below the mean. The number of capability sigmas is given by the value of the SIGMAS subcommand, which is 3 by default.

NONE. Specifies that no reference lines will be displayed. This is an alternative to SL and/or SIGMAS and cannot be used in combination with them.