This error occurred because the expression is not complete.
This error occurred because the expression is not valid Maple syntax. Use the help system to find the valid Maple syntax for the operation you wish to perform. The best ways to construct expressions in 2-D math are to use the Expression palette or the command completion templates.
If you want to show an expression that you do not want Maple to execute, there are two solutions.
Solution 1: To write mathematical notation within a paragraph, use a text region. Type the paragraph, switching the entry mode from Text to Math as needed. For example,
Use the ⊥ symbol to indicate that two lines are perpendicular.
Solution 2: Select the expression, then from the Format menu select Convert To>Atomic Identifier. This turns the expression from a mathematical object to a single name. Maple no longer tries to parse the expression. Now, when it is executed there is no parse error.