A fixed-width file use a fixed column width for each column (though not all columns necessarily have the same width) and pads the remaining space on the left or on the right, usually with spaces:
287540 Smith Jones Accountant $55,000
204878 Ross Betsy Senior Accountant $66,000
208417 Arthur Wilbur CEO $123,000
This example use golang package github.com/davidburil/fixedwidth