Certain messages require a "target". In particular, RV-C defines a set of PGNs for "proprietary" messages - messages that are specific to a particular make and model. These messages have to be directed to that specific device - in contrast to most messages which are heard by every device on the network.
By default, the target is the device selected by the user in the Device List when they start the script. The script can change this using the TARGET command. It has two forms: TARGET ADDRESS and TARGET "name".
: Set target to the generator (address 40)
TARGET 40
SEND EFXX 00 00 00 00 00 00 00 00
: Set target to the ACME 2000
TARGET "ACME 2000"
SEND EFXX FF FF FF FF FF FF FF FF
When Omniscope encounters a SEND command with the EFXX PGN, it substitutes the target address for the XX's. Thus the first SEND command shown is equivalent to "SEND EF40 00 00 00 00 00 00 00 00".