The Collapse function converts coincident entities, i.e. entities that are very close to each other, into one.
The ImportTolerance variable (see Preferences) determines which entities will be collapsed. Where the distance between two points is less than the tolerance, they will be converted to one. With lines and surfaces, the maximum distance between both entities is calculated and if it is less than ImportTolerance, they are converted to one.
Select the type of entities - point, line, surface or volume - when in geometry mode. All the lower entities that belong to the selected entities will automatically be computed. On pressing escape, the collapse operation will be performed.
The Model option performs the operation over all the geometrical entities in the model.