An N+1st attempt to summarize information helping to optimize taxes arising from investments with ETFs.
Some preliminary comments: I am going to mostly refer to MSCI indices. Their definition/composition can be found at msci.com (search for pdf factsheets).
MSCI ACWI is all-countries index: 50 countries, 23 Developed Markets, 27 Emerging Markets. An up to date country weights can be found at
ACWI | SPYY : SPDR® MSCI ACWI UCITS ETF
(see Holdings → Geographical Weights).