What is a flat file?
Flat files are rows of text that convey pre-defined information. Typically, a flat file will begin with a line identifier, letting a system know what string of data is about to follow. A Flat File can contain multiple lines of data with each line containing different line identifiers. Each line can have many fields of data, separated by a special character. Many systems use Flat File formats to import and export data as it is very favorable to understand easily for a machine.
In order for a Flat File to work properly, the sending or receiving system has to understand the definition of that file. Since there are no indicators on what each field represents within the file itself, something called a Multirecord Definition must be created in order for a system to understand the meaning of each field.