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An expression is a structured tree of symbols that denotes a (possibly empty) set of values when evaluated in a context.
ValueSpecification (from Kernel ) on page 140
An expression represents a node in an expression tree, which may be non-terminal or terminal. It defines a symbol, and has
a possibly empty sequence of operands that are value specifications.
Issue 9191 - change lower multiplicity to 0
• symbol: String [0..1] The symbol associated with the node in the expression tree.
• operand: ValueSpecification [*] Specifies a sequence of operands. Subsets Element::ownedElement.
No additional constraints
An expression represents a node in an expression tree. If there are no operands, it represents a terminal node. If there are
operands, it represents an operator applied to those operands. In either case there is a symbol associated with the node.
The interpretation of this symbol depends on the context of the expression.
By default an expression with no operands is notated simply by its symbol, with no quotes. An expression with operands is
notated by its symbol, followed by round parentheses containing its operands in order. In particular contexts special notations
may be permitted, including infix operators.