I'm not sure, but think that SAM-implementation is based on System Monitor (https://docs.intersystems.com/iris20194/csp/docbook/DocBook.UI.Page.cls?KEY=GCM_healthmon) in some fashion. Could you clarify your task? Do you want to know an exact name of Global where samples are stored?  For what?
Link you've shared describes how to expose your custom numeric metric that could be read by Prometheus, for instance, and then stored there.

Hi David,
Thanks -) Regarding a meaning - it's taken from mgstat source-code (%SYS, routine mgstat.int).
Starting point was a line 159 in my local Cache 2017.1:

i maxeccon s estats=$p($system.ECP.GetProperty("ClientStats"),",",1,21),array($i(i))=+$system.ECP.NumClientConnections(),array($i(i))=$p(estats,",",2),array($i(i))=$p(estats,",",6),array($i(i))=$p(estats,",",7),array($i(i))=$p(estats,",",19),array($i(i))=$p(estats,",",20)

Then I guessed a meaning from a subroutine "heading" (line 289).

But the best option for you, I think, is to ask WRC. Support is very good.