The expression editor is the main tool in which you write and edit expressions.
There are several ways to display the expression editor. Each way does something slightly different:
To display the expression editor without a target parameter or setting a default expression, choose View 
Animation Expression Editor from the main menu or Animation Expression Editor from the Animation panel. You can then select a target as described in Selecting or Changing the Target.
Select an object and press Ctrl+9 to open the expression editor in a floating window.
Create a default expression — see the following section, Creating an Equal (=) Expression.
Edit an existing expression — see Editing an Existing Expression.
Open the animation editor and choose Editor Expression Editor.
| A |
The target shows which parameter is controlled by the expression. See Selecting or Changing the Target for more information. |
| B |
The command bar contains menus of commands, including functions. |
| C |
The value box shows the value of the expression at the current frame. |
| D |
The message pane updates as you work, letting you know whether the expression is valid. Press Ctrl+G to switch between this pane and a graph of the resulting expression values. |
| E |
The editing pane is a text editor where you enter an expression by typing or choosing items from the menus on the command bar. See Writing Expressions for more information. |
