Tektronix AFG2021 Programmer's Manual page 26

Command Syntax
General rules for using
SCPI commands
2-8
The following table lists the available units.
Table 2-5: Available units
Symbol Meaning
dB decibel (relative amplitude)
dBm decibel (absolute amplitude)
DEG degree (phase)
Hz hertz (frequency)
PCT percent (%)
s
second (time)
V volt
You can omit a unit in a command, but you must include the unit when using a SI
prefix. For example, frequency of 15 MHz can be described as follows
15.0E6, 1.5E7Hz, 15000000, 15000000Hz, 15MHz, etc.
("15M" is not allowed.)
Here are three general rules for using SCPI commands, queries, and parameters:
You can use single (' ') or double (" ") quotation marks for quoted strings, but
you cannot use both types of quotation marks for the same string.
correct "This string uses quotation marks correctly."
correct 'This string also uses quotation marks correctly.'
incorrect "This string does not use quotation marks correctly.'
You can use upper case, lower case, or a mixture of both cases for all
commands, queries, and parameters.
:SOURCE:FREQUENCY 10MHZ
is the same as
:source:frequency 100mhz
and
SOURCE:frequency 10MHZ
NOTE. Literal strings (quoted) are case sensitive, for example, file names.
No embedded spaces are allowed between or within nodes.
correct
:OUTPUT:FILTER:LPASS:FREQUENCY 200MHZ
incorrect
:OUTPUT: FILTER: LPASS:FREQUENCY 200MHZ
AFG2021 Arbitrary Function Generator Programmer Manual