### Instruction:
Can you tell me about the Porsche 993 targa?

### Input:
The Targa version of the 993 was introduced in the 1996 model year and was the debut of the so-called "greenhouse" system - a retractable glass roof, a design continued on the 996 and 997 Targa. The glass roof retracts underneath the rear window, revealing a large opening. This system was a complete redesign, as previous Targa models had a removable roof section and a wide B-pillar functioning as a roll bar. The new glass-roof design allowed the 993 Targa to retain the same side-on profile as the other 911 Carrera variants and finish without the inconvenience of storing the removed top of the old system. The Targa is based on the 993 Carrera cabriolet with the Targa glass roof replacing the fabric roof.

### Response:
In 1996, Porsche introduced the 993 in a targa variant. Though targas had been around from Porsche for decades, there was a new approach with the 993 model. They implemented a so-called "greenhouse" system whereby the glass roof retracts underneath the rear window, revealing a large opening. This allowed the 993 to have the same side profile as the coupe models, but without the inconvenience of storing the removed top of the old system.