text: Variations in moveable, removable and transparent roof panels continued. The Ford Lincoln X-100 concept car of 1953 revisited the Sedanca style for a non-chauffeured vehicle as it had a retractable transparent targa top which inspired later fixed moonroof panels on 1954 production vehicles. In 1961 Triumph launched the TR4 with a removable hard top roof split into two sections. The rear part, incorporating the rear window, could be left on the car when the centre piece was removed creating a Sedanca layout. This concept was resurrected again in 1966 when Porsche launched a version of its 911 sports car that established the term Targa, trademarked by Porsche. This bore even more of a resemblance to the traditional Sedanca form, as the car had both a permanently fixed roll-over hoop, and rear seats. While in 1969 Lamborghini showed the first full-roof framed transparent-panel roof, heralding the modern panoramic roof, on an Espada.
  Sunroofs, by historical definition are opaque. Today, most factory sliding sunroof options feature a glass panel and are sometimes marketed as moonroofs, a term introduced in 1973 by John Atkinson, a marketing manager at Ford for the Continental Mark IV. For the first year, Ford sent out its Mark IVs to American Sunroof Company for offline installation.
  Variations of both the sunroof and moonroof have become the norm in both factory installed and aftermarket offerings, creating a wide range of features and choices. Sunroof systems may be manual or electric, while most moonroof systems are electric/electronic. Manual sunroofs may be lever actuated, as in venting type pop-ups, manual lever or crank operated for sliding systems. Electric roof systems are usually cable driven by a motor and feature some form of sliding opening. Most moonroof systems today are electric and have either a combination pop-up/inbuilt or a pop-up/spoiler configuration (see sunroof types below).