If several sequences in a routing are to be carried out in parallel, the lead times of these sequences generally differ. As a result, floats occur within the sequences. The alignment key controls whether these floats are to be positioned at the start or at the finish of the sequence:

• If the sequence is aligned with the earliest possible date, the float is at the finish of the sequence.
• If the sequence is aligned with the latest possible date, the float is at the start of the sequence.

An alignment key is assigned to the standard sequence and to each of the parallel sequences. The following figure shows the relationship between the alignment key and how sequences are scheduled. The floats are hatched in the graphic. Whereas the three parallel sequences are aligned with the earliest possible date, the standard sequence is aligned with the latest possible date.