Entity selection: Circumstances and selection modes
Introduction
The most part of actions for handling the entities require the selection of entities .
Indeed:
- to modify the coordinates of a point, you should select the corresponding point
- to add a line (segment), you should define extremity points and then select starting point and ending point
- …
The different selection circumstances and selection modes are presented in this paragraph.
Selection circumstances: overview
Selection of entities could be done before or after the activation of a command; it could also be done, during an operation of creation.
These various circumstances of selection are presented through examples in the table below.
| Selection before activation of a command | |
|---|---|
|   | … Activation of a command: 
 | 
| Selection after activation of a command (via selection box) | |
|---|---|
| Activation of a command: 
 |   | 
| Selection during an operation of creation | |
| Activation of a command: 
 |   | 
Selection modes: overview
Selection of entities could be done with the following different selection modes:
- graphic selection (directly with the mouse)
- in the data tree for all entities
- in the graphic area for graphic entities
- identifier selection (by name / by number )
- criterion selection* (by relation / by … identical characteristics )
* the advanced selection is detailed in § Entity selection: Selection by criterion
Summary
The different selection modes proposed function of selection circumstances are gathered in the table below.
| Selection circumstances | … | Selection modes | 
|---|---|---|
| Selection before activation of a command | graphic | |
| Selection after activation of a command | Selection box | graphic by identifier (name/number) by criterion | 
| Selection during an operation of creation | Specialized box | graphic by identifier (name/number) |