Agilent Technologies 54753A Programmer's Reference Manual page 4

Introduction
[ ] Square brackets indicate that the enclosed items are optional.
{ } When several items are enclosed by braces, one, and only one of these
elements may be selected.
Definitions d ::= A single ASCII numeric character, 0-9.
n ::= A single ASCII non-zero, numeric character, 1-9.
<NL> ::= Newline or Linefeed (ASCII decimal 10).
<sp> ::= space character.
<white_space> ::= space(s) and tabs.
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