target; destination of instructions
Refers to the person, device, or location to which instructions or commands are directed. Often used in technical or business contexts.
The target of this command is the printer.
If you specify the wrong destination for the instructions, it won't work correctly.
送信先 means a transmission destination, often for data or messages, whereas 指示先 is broader and can include devices or people receiving instructions.
Compound of 指示 (instruction) and 先 (destination, target). The exact historical derivation is uncertain, but the meaning is transparent from its components.