Notation Conventions

{x}*	zero or more occurrences of x
{x}+	one or more occurrences of x
[x]	zero or one occurrence of x
x \| y	either x or y can appear, but not both of them
x::= y	x is defined by y
<x>	x is scalar
‘x	x is symbol
:x	x is keyword
(x)	x is a list element