Not to offend ICAO, but it seems to me that, no sooner than the time everyone understands what is required to operate in a particular airspace or state, ICAO decides to scrap that standard and create an entirely new one (from MNPS to RNP to PBN). Combine that with the fact that each state has the discretion to deviate from the ICAO standards and it becomes even more confusing and frustrating.