Interval tree clocks
A stamp pair: http://gsd.di.uminho.pt/members/cbm/ps/itc2008.pdf#page=5
https://blog.separateconcerns.com/2017-05-07-itc.html
https://github.com/ricardobcl/Interval-Tree-Clocks
https://github.com/fgrid/itc
https://cs.stackexchange.com/questions/90255/interval-tree-clocks