I do not have a copy of the MSA manual, so page 20 means little to me. Perhaps someone who does can supply the information or if you can provide me with details of "Data Category", perhaps I can help.
Sorry,I have no details about Data Categories. There are some applications of Data Category only. Maybe someone else will give me some information. Thank you very much.
I believe this refers to having your data divided into intervals such as 1.0-1.49, 1.5-1.99, etc. This is done when from a histogram you want to determine properties of a distribution. It also can give you better "resolution" of your data if you can divide up your data set into more categories or intervals. A standard statistics book should give you more details. Look under "distributions" or "histograms" analysis.