I've read that data can be divided into 4 types regarding their scales: Nominal, ordinal, interval, and ratio. It is stated that nominal data distinguishes an object / event from another ones based on their kinds, e.g. : Male / Female, Village / City. So, can we call animal classification table as nominal table instead of qualitative table? Is either of them a mathematics formal term? I have the difficulty going with qualitative table because I plan to include some alphabet table, like Arabic letters: How to write it in various places (they are determined by their positions), how to pronounce, how to spell in alphabet, etc. Can that kind of table even be referred as qualitative?

Another question. There are some kinds of charts, namely line chart, stem and leaf plot, box plot, pictogram, bar chart, and pie chart. Each of them will be made into a sub-chapter in a chapter titled "Learning the Forms of Charts". Can some of those six sub-chapters be merged so the chapter will be more simplified? Like if a type of chart is a sub-type of the other ones. Thanks for your help.