For 737,it is based on one engine at TOGA,flaps 15.
FACT!
No, that is not correct.
Ref 8260.52 and PansOps 8168. Describes terminal procedure designs and the parameters. Currently, EO operations are not included in terminal design criteria. EO are referenced in airport operations as an operator requirement, but this design must be done by others, on a specific basis.
FAR Part 25 Airworthiness, describes how V 1.3 is determined.
"Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3 Vsoat the maximum certificated landing weight. VREF, Vso, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry."