Texas Instruments TITANIUM TI-89 User Manual page 566

In the Data/Matrix Editor, you can enter the scores and the category values in two
columns.
Test scores
c1
85
97
92
88
90
95
79
68
92
84
82
To use category values, specify the category column and the category values to include
in the analysis when you perform a statistical calculation or define a stat plot.
Statistics and Data Plots
Category values
c2
1
3
2
3
2
1
4
2
4
3
1
566