In 2002, the National Kidney Foundation published treatment guidelines that identified five stages of Chronic Kidney Disease (CKD) based on declining GFR measurements. The guidelines recommend different actions based on the stage of kidney disease.
CSV (Comma Separated Value) was a file format devised to store tabular data. It uses commas to separate each entry in a row and the newline symbol to go to the next row. Excel is a more recent spreadsheet application from Microsoft and it saves the data with its own file format.
A CSV file is one of the most common flat files, as it represents relational data in a text file. Another flat file example is a delimited file that contains one or multiple records that are separated by a specific character, such as a tab.