A.2.6 Bracketed Objects
Bracketed objects use explicit left and right delimiters to indicate their extent. They can appear anywhere within Mathematica input, and can be nested in any way.
The delimiters in bracketed objects are matchfix operators. But since these delimiters explicitly enclose all operands, no precedence need be assigned to such operators.
Bracketed objects without comma-separated elements.
Comments can be nested, and can continue for any number of lines. They can contain any 8- or 16-bit characters.
Parentheses must enclose a single complete expression; neither (e,e) nor () are allowed.
Bracketed objects that allow comma-separated elements.
Throughout this book the notation ... is used to stand for any sequence of expressions.
, ... can include any number of elements, with successive elements separated by commas.
} is List, a list with zero elements.
, ... can be entered as \[LeftAngleBracket]
, ... \[RightAngleBracket].
The character \[InvisibleComma] can be used interchangeably with ordinary commas; the only difference is that \[InvisibleComma] will not be displayed.
When the delimiters are special characters, it is a convention that they are named \[LeftName] and \[RightName].
\( ... \) is used to enter boxes using one-dimensional strings. Note that within the outermost \( ... \) in a piece of input the syntax used is slightly different from outside, as described in Section A.2.9.
Bracketed objects with heads.
Bracketed objects with heads explicitly delimit all their operands except the head. A precedence must be assigned to define the extent of the head.
The precedence of h[e] is high enough that !h[e] is interpreted as Not[h[e]]. However, h_s[e] is interpreted as (h_s)[e].