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The normal selection mode is SwapSelection'Swap Selection': If one entity is selected a second time, it becomes deselected and its color reverts to normal. In addition there are the options AddToSelection and RemoveFromSel, the former always adding to the selection, the latter always removing entities from the selection.
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If a layer named 'a' exists, it is possible to select all entities belonging to that layer with command: layer:a . Using the command layer: selects all entities not belonging to any layer.
Another way of selecting points or nodes is to write:
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When selection lines or surfaces (geometry or mesh) it is possible to pick one or more entities, and use 'ConnectedTangentConnected Tangent' to select its connected neighbor entities, if the angle between them is smooth enough. This is very interesting for example to select coplanar parts.
It is possible select a group on entities that are parents of a single 'lower entity' by using 'ParentsOfParents Of', and selecting the lower entity. (e.g. to select all surfaces that are sharing some line)
In some commands, another item is added to the selection group. This item, called AllTypes'All Types', means that entities of all levels (points...volumes) will be selected at the same time. In this case, only selection via a dynamic box is possible in the graphical window and all entities (points, lines, surfaces and volumes) in the box are selected.
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