The export file consists of a sequence of bytes that can also be considered to be a sequence of commands in machine language. These commands consist of:

• Operator codes

• Operator parameters (operands)

The first two bytes in a command contain the operator code. Several bytes follow the operator code and these form the operator parameter. The operator parameters represent the operands. However, there are also operators without operands.

An export file begins with a start sequence, the preamble. The preamble is followed by personnel numbers. The postamble constitutes the end sequence.

The preamble shows the start of the export file. The operands in the preamble contain information on the export program (for example, creation date). The export file always starts with a preamble.

Each personnel number begins with a BOP operator (begin operator for personnel number). The payroll period that the BPE operator (begin operator period) introduces follows. Within the payroll periods there is the actual export data, which is grouped together in blocks. The EPE operator (end operator personnel number) forms the end of the payroll period. The EOP operator (end operator for personnel number) is at the end of the personnel number.

The postamble is at the end of the export file. The postamble begins with the BPO operator (begin operator for postamble), followed by an operand. The EPO (end operator for postamble) operator forms the end of the postamble.