Files with a comma separated value (*.csv) extension are in plain text. They contain characters stored in a flat, nonproprietary format and can be opened by most computer programs. Each *.csv file contains a set of tabular data, with each record delineated by a line break and each field within a record delineated by a comma. A field that contains commas as part of its content has the additional delineation of a quote mark character before and after the field's contents. When a quote mark character is part of a field's content, it is included as two consecutive ""quote mark"" characters.
Computers with Microsoft Excel installed open *.csv files in Excel by default, with the fields automatically arranged appropriately in columns. Other database programs also open *.csv files with the fields appropriately arranged.
There are 23 Excel files ("NSDUHsaeExcelTab#-2007.xlsx"), one for each table. Each file has one worksheet, containing the table title, table notes, column headings, and data. The 23 CSV data files ("NSDUHsaeExcelTab#-2007.csv") reflect the 23 Excel files, containing the table title, table notes, column headings, and data.