HP 8163A Programming Manual page 23

Introduction to Programming
Programming and Syntax Diagram Conventions
The characters between angled brackets (<...>) indicate the kind
of data that you should send, or that you get in a response. You do
not type the angled brackets in the actual message.
Descriptions of these items follow the syntax description. The
following types of data are most commonly used:
string is ascii data. A string is contained between double
quotes ("...") or single quotes ('...').
value is numeric data in integer (12), decimal (34.5) or
exponential format (67.8E-9).
wsp is a white space.
Other kinds of data are described as required.
The characters between square brackets ([...]) show optional
information that you can include with the message.
The bar (|) shows an either-or choice of data, for example, a|b
means either a or b, but not both simultaneously.
Extra spaces are ignored, so spaces can be inserted to improve
readability.
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