Extended file functions read and access files in CSV format (comma-separated format) or a fixed-length format. You can use them to read multi-column values in sequential or random order. They are very useful when you want to parameterize your workload with values that are stored in files. For example, you can use these functions to read a Web Server log and use the URL strings stored in the log inside your Web transactions; or you can use them to load valid pairs of multi column data from a file to parameterize data values in your script (for example, valid user/password pairs).