Equation F.31. Keys f₂, f₃, f₄

Curve 60. Key for inside look revolving 180º f₂
Curve 61. Key for inside look revolving 270º (moving) f₃
Curve 62. Key for inside look revolving 270º (stationary) f₄

Equation F.32. Tape Σ₁

Equation F.33. 2 centre-handle turning-locks Z₃Z₄, key f₂, tape Σ₃

Equation F.34. Padlock З₀

Equation F.35. 2 door straps d₀, d₁, 2 locks З₁, З₂

Equation F.36. 2 door straps, pawl, padlock, key (d₀З₁d₂)