fanout layout
Fanout, as used in DXP, places short track segments and vias to make connections to inner rows of pins on high pin count devices, or to pins on a device with very closely spaced pins. It is an attempt to make it easier to connect traces to devices with close spaced, or multiple rows of, pins.
An example would be a BGA package. When routing, you need to connect pads that are arranged in concentric rings. To get traces to the inner rings of pads, you sometimes have to run traces from the second ring pads between the pads for the outside ring of pads - that is called fanning out the second ring connections.
Likewise, if the pins of a QFP device are very close together, there isn't enough room to place vias with the same spacing as the pins in order to make connections. In this case the vias would be placed away from the device pins at a distance that allowed proper spacing clearance. Traces from the actual device pins would then be "fanned out" from the device pins to the vias.
The best analogy I can think of is for you to hold out your hand and spread your fingers apart. You fingers in that position are "fanned out" from your palm. The fanout function in DXP does the same sort of thing with traces and vias to make connections easier to route.