...and I forgot to add, the rules to be followed are generally not to be found in FARs, JARs etc, but are agreed upon following negotiation with certifying and local authorities.
Plenty of guidance material exists outside of the rules (Advisory Circulars, AMJs, Authority policy documents etc), but careful negotiation is required to understand their many different interpretations.
For example, engines must be tested for capability to achieve thrust used for performance (engine temperature limits, powersetting stability etc) within 3000ft of the certifying altitude, according to AC 25-7 and many policy documents, but if you intend to fly from La Paz, expect the authorities to expect you to test/demonstrate there!