An introduction to the scpi language, An introduction to the scpi language 111, Standard commands for programmable instruments – Agilent Technologies E3632A User Manual
Page 114: Tree system, Subsystems, Colon

Chapter 4 Remote Interface Reference
An Introduction to the SCPI Language
111
4
An Introduction to the SCPI Language
SCPI (
Standard Commands for Programmable Instruments
) is an ASCII-
based instrument command language designed for test and measurement
instruments. Refer to ‘‘Simplified Programming Overview’’, starting on page 78
for an introduction to the basic techniques used to program the power supply
over the remote interface.
SCPI commands are based on a hierarchical structure, also known as a
tree
system
. In this system, associated commands are grouped together under a
common node or root, thus forming
subsystems
. A portion of the
SOURce
subsystem is shown below to illustrate the tree system.
[SOURce:]
CURRent {
|MIN|MAX|UP|DOWN}
CURRent? [MIN|MAX]
CURRent:
TRIGgered {
|MIN|MAX}
TRIGgered?{MIN|MAX}
VOLTage {
|MIN|MAX|UP|DOWN}
VOLTage? [MIN|MAX]
VOLTage:
TRIGgered {
|MIN|MAX}
TRIGgered? {MIN|MAX}
SOURce
is the root keyword of the command,
CURRent
and
VOLTage
are
second-level keywords, and
TRIGgered
is third-level keywords. A
colon
(:)
separates a command keyword from a lower-level keyword.