HP 1650B Programming Reference Manual page 298

Device Listening The listening syntax of IEEE 488.2 is designed to be more forgiving than
Syntax
the talking syntax. This allows greater flexibility in writing programs, as
well as allowing them to be easier to read.
Upper/Lower Case Equivalence. Upper and lower case letters are
equivalent. The mnemonic SINGLE has the same semantic meaning as
the mnemcnic single.
white space > . <white space > is defined to be one or more characters
c
from the ASCII set of 0 - 32 decimal, excluding 10 decimal (NL). <white
space > is used by several instrument listening components of the syntax
It is usually optional, and can be used to increase the readability of a
program.
Figure A-2. <white space >
HP 1650B/HP 1651B
Message Communication and System Functions
Programming Reference
A-6