Docking scaffold

From Memory Alpha, the free Star Trek reference

In the mirror universe, a docking scaffold was a structure attached to a docking bay of Terok Nor, where the Defiant was constructed in 2371 and 2372. Once the Defiant became operational, the docking scaffold was jettisoned prior to launch. (DS9: "Shattered Mirror")

The docking scaffold (like the Defiant) was rendered as a computer generated image. (Star Trek: Deep Space Nine Companion)