From SKYbrary Wiki
STD: Standing - Prior to pushback or taxi, or after arrival, at the gate, ramp, or parking area, while the aircraft is stationary.
This phase of flight includes the following sub-phases:
- Engine(s) Not Operating
- Engine(s) Start-up
- Engine(s) Operating
- Engine(s) Shutdown
- Engine shutdown is from the start of the shutdown sequence until the engine(s) cease rotation