It takes years for the line units to develop.

The new aircraft began to reach front line units during summer 1944.

Moreover, the front line units in the West were complaining about the poor numbers and performance of aircraft.

They were dismissed and sent back to their front line units.

Supplies had to be transported to the various front line units.

Swedish first line units would at times lose equipment and material that was needed on the other side of the border.

Initially, they were identified by letters and numbers, like line units.

Tu-4s withdrawn from front line units were used for transport duties.

He was part of an offensive line unit that allowed just 35 sacks in 480 pass plays on the season.

In this type of support system the front line units are considered as a layer just like all the other layers.