Plain English Meaning

A regular yellow taxiway centerline that, near a runway, has dashed yellow lines added on both sides of it. These extra dashes are a heads-up that you are getting close to a place where you must stop and check before crossing onto a runway.

Full Definition

A taxiway centerline marking that, in the area approaching a runway holding position marking, is supplemented by a pair of yellow dashed lines flanking each side of the normal solid yellow centerline. The enhanced portion extends up to 150 feet prior to the holding position marking, providing a visual cue that the aircraft is approaching a runway hold short location.

Context Anchor

Seen while taxiing toward a runway entrance or runway crossing, just before the runway holding position marking.

Derivation

Enhanced' comes from Old French enhauncier, meaning to raise or heighten. Here, the centerline is 'raised' visually by adding the flanking dashes — making the approaching line harder to miss.