code: @Pure
  	public IntegerProperty z1Property() {
  		if (this.p1.z == null) {
  			this.p1.z = new SimpleIntegerProperty(this, MathFXAttributeNames.Z1);
  		}
  		return this.p1.z;
  	}
docs: Replies the property that is the z coordinate of the first segment point.
  
  @return the z1 property.