When selecting "Block and all hierarchy underneath" or "Board", only the current schematic is checked, lower levels in the hierarchy are not checked.
Actually DRC is not even checking all pages on the same level. The situation is like this:
Checking individual sheets I get drc-823 warnings on many sheets.
But checking the block or the board I get drc-823 warnings only for 2 sheets.
By the way, "Table 3-11. DRC Settings Tab Options" in the "DxDesigner Reference Manual For Expedition Flow, EE 7.9.5" uses the wording "selected sheet", "selected block" and "selected board".
How are items selected for DRC?
It seems to me that DRC is always checking the page or block that is open in the schematic editor window.
Update 6 for EE7.9.5