Folding stool

Claim 1

A PORTABLE FOLDING STEP LADDER WHICH HAS A. A FLOOR-SUPPORTED RIGID CAGE-LIKE SELF-STANDING BASE STRUCTURE HAVING A TOP PLATFORM. B. A STAIR NORMALLY CAGED AND FOLDED WITHIN SAID BASE STRUCTURE AND ADAPTED TO BE UNFOLDED BY AN OUTWARD MOVEMENT FROM ITS CAGED POSITION TO ITS EXTENDED POSITION SO AS TO ENGAGE THE FLOOR OUTSIDE THE BASE AREA AND TO PROVIDE A STEP WHICH (X) IS AT A HEIGHT INTERMEDIATE THE FLOOR AND THE PLATFORM AND (Y) PROJECTS OUTWARDLY FROM THE BASE STRUCTURE. C. A SET OF TWO INTER-ENGAGEABLE PARTS WHICH ARE CARRIED RESPECTIVELY BY THE BASE AND THE STAIR AND WHICH, IN THE EXTENDED POSITION, ARE ADAPTED TO ENGAGE EACH OTHER TO FORM A LOCK FOR PREVENTING FOLDING MOVEMENT OF THE STAIR. D. SAID INTER-ENGAGEABLE PARTS BEING ADAPTED TO BE DISENGAGED BY A LIMITED UPWARD MOVEMENT OF THE STAIR RELATIVE TO THE BASE-STRUCTURE SO AS TO RELEASE SAID LOCK AND ALLOW THE STAIR TO BE FOLDED AND THEREBY CAGED WITHIN THE BASE STRUCTURE. E. ONE OF SAID INTER-ENGAGEABLE PARTS INCLUDING A CAM CO-OPERATING WITH THE OTHER INTER-ENGAGEABLE PART FOR AUTOMATICALLY EFFECTING SAID ENGAGEMENT AS AN INCIDENT TO THE OUTWARD MOVEMENT OF THE STAIR.