# Program Message Terminator

SCPI Basics

- Program Message Terminator
- Short or Long Forms
- White Space
- Combining Commands
- Adding Parameters to a Command
- String Arguments
- Numbers
- Infinity Representation
- Queries
- Endianness of Returned Binary Block Data
- NaN (Not A Number)
- Sequential and Overlapped Commands
- SCPI Tree

SCPI commands sent within a data message are executed after the program message terminator is received. The terminator may be one of the following types:

- ASCII NL (new line) character ("\n", decimal 10, hex 0A)
- Combination CR (carriage return) and NL characters ("\r\n", decimal 13/10, hex 0D/0A). If you use the Keysight IO Monitor that is provided with Connection Expert, note that the CR character is represented by a "." (period) within the monitor.
- EOI (End-Or-Identify) asserted in the SCPI interface

Asserting the EOI sets the EOI control line low on the last byte of the data message. The NL (New Line) terminator has the same function as an EOS (End Of String) and EOT (End Of Text/Transmission) terminator.