2 Introduction to Programming44 Keysight Models 6811C, 6812C, and 6813C Programming GuideHeadersHeaders are instructions recognized by the ac source. Headers (which aresometimes known as “keywords”) may be either in the long form or the short form.The SCPI interface is not sensitive to case. It will recognize any case mixture, suchas TRIGGER, Trigger, TRIGger.Message unit separator The semicolons in VOLT:LEV 80; and PROT 88;Root specifier The colon in PROT 88;:CURR?Query indicator The question mark in CURR?Message terminator The (newline) indicator. Terminators are not part of the SCPI syntax.Long form The header is completely spelled out, such as VOLTAGE, STATUS, and DELAY.Short form The header has only the first three or four letters, such as VOLT, STAT, and DEL.NOTE Short form headers result in faster program execution.HeaderconventionIn the command descriptions in Chapter 3, “Language Dictionary” of this guide, headersare emphasized with boldface type. The proper short form is shown in upper-case letters,such as DELay.HeaderseparatorIf a command has more than one header, you must separate them with a colon (VOLT:PROTOUTPut:RELay:POLarity).OptionalheadersThe use of some headers is optional. Optional headers are shown in brackets, such asOUTPut[:STATe] ON. As previously explained under “The effect of optional headers” onpage 39, if you combine two or more message units into a compound message, you mayneed to enter the optional header.
