10. The method of claim 9 wherein the first indicator is a tab.
9. A method for navigating through selection modes for a displayed representation of computational construct that represents a unary operator, the unary operator having an operand, the selection modes including a left selection mode, a tree selection mode, a crown selection mode, and a right selection mode, the method comprising: setting a current selection to a selection of the computational construct representing the unary operator and its operand in the left selection mode so that, when a computational construct representing a binary operator is specified, the unary operator will be a right operand of the binary operator; when the current selection is the selection of the computational construct representing the unary operator and its operand in the left selection mode and a user inputs a first indicator, setting the current selection to a selection of the computational construct representing the unary operator and its operand in the tree selection mode so that, when a computational construct is specified, the computational construct for the unary operator and its operand is replaced by the specified computational construct; when the current selection is the selection of the computational construct representing the unary operator and its operand in the tree selection mode and the user inputs the first indicator, setting the current selection to a selection of the computational construct representing the unary operator in the crown selection mode so that, when a computational construct is specified, the computational construct for the unary operator is replaced by the specified computational construct; when the current selection is the selection of the computational construct representing the unary operator in the crown selection mode and the user inputs the first indicator, navigating a displayed representation of the operand; and when the navigating of the operand is completed by the user inputting the first indicator, setting the current selection to a selection of the computational construct representing the unary operator and its operand in the right selection mode so that, when a computational construct representing a binary operator is specified, the unary operator and its operand will be a left operand of the binary operator.