How are close prices for ETF groups calculated?

Research
1

I can’t find the link, but I remember from previous discussions that the closing prices for stock sector and industry groups was the cap-weighted total return index based on some arbitrary initial values and some size/liquidity filters.

E.g,. close(0,#SubIndustry)

Can anyone link me to the exact methodology?

Also, how does this work for ETF/CEF scope groupings, such as #assetclass? How are peer-group weighted returns calculated if P123 doesn’t have NAV data? Or is it doing something else in this context?

Thanks!