Thermally insulated sliding and lift-and-slide system with a solid vent frame and minimal face widths. The sliding door system creates generous, unimpeded, and smooth-running passage openings (with three tracks, up to two-thirds of the unit width) and requires a minimum amount of space. Since the sliding leaves run on one level, there are no door leaves opening inward or outward. In a closed state, the aluminum system offers excellent thermal and sound insulation owing to perfect weather tightness. There is virtually no limit to design freedom. The sliding door constructions can be perfectly tailored to individual customer requirements using sash bars, feature glazing beads, and stainless steel fittings. The system offers ideal project solutions in the private housing sector (including conservatories), the hotel and catering sector, and in office buildings as sliding windows.