2.1.37 [ECMA-262-1999] Section 12, Statements

V0054:

Syntax

Statement :

Block
VariableStatement
EmptyStatement
ExpressionStatement
IfStatement
IterationStatement
ContinueStatement
BreakStatement
ReturnStatement
WithStatement
LabelledStatement
SwitchStatement
ThrowStatement
TryStatement
__DebuggerStatement__
__FunctionDeclaration__

JScript 5.x allows a FunctionDeclaration to occur as a Statement.