This parameter is available from the Z Plane tab:
Type Select the method used to generate the analysis model:
Automatic Used on surface models where the holes and/or sides have not been defined (unnecessary for manufacture) and the model will find the top and bottom extends of the model. Only use this option when model has not been completely defined.
Male Used on surface models where the analysis model meets with the bottom plane on the outer edge.
Female Used where the outer walls are not to be selected for manufacture and therefore are not included in the analysis model.
Specify Plane Use this option if you want to restrict the analysis to areas either above or below a set level, using the Analyse Below Plane and Z Level parameters.