The advanced mash efficiency page has received some major and minor updates.
The first major update is that the tool follows John Palmer's example more closely (2001, p. 148 - 152). The older version calculated gravity points for an entire batch. For example, 5 gallons at 1.037 would be 185 gravity points (theoretical maximum). The current version expresses this per gallon or per liter, which is how Palmer's calculations work. The math is really equivalent, but it might be easier to understand when expressed per volume unit.
A second major update is the metric calculations use L degrees per kilogram. The previous version just converted metric units to imperial (US) units, then did the calculations with the imperial units. This crude approach worked for calculating efficiency, but it was perhaps disappointing to people who use metric units.
There were a few other minor tweaks. Malt extracts were moved from the base malts to the sugar options. The description of the calculations was edited to improve clarity and explain metric calculations.
https://topdownbrew.com/MashEfficiencyAdvanced.html
Palmer, J. (2001). How to Brew. Second edition. Defenestrative Publishing Co.