Hand and Foot Modifier FA -F9 and T1 - T9. E1 - E4, FA - F9, TA - T9 Level II Modifier. E1-E4 Anatomic modifiers which are associated with the eyelid. FA, F1- F9 Anatomic modifiers which are associated with the fingers. TA, T1- T9 Anatomic modifiers which are associated with the toes.
X-bar and R Control Chart Issues and Resolution. X-bar and R control charts are used in quality control to identify when special cause or out-of-control conditions occur in time-series data so that timely corrective actions can be taken to resolve problems.
For completeness, we could also state that whereas bar charts have bars all the same width, it is possible on a histogram to have bars of unequal width, in which case it would be the area of the bars that we would be interested in.