Recalculate and Recalculate Hard in Calc

All,

I’m having a problem understanding the Help information for these 
functions (search for “recalculate” in the Help index).

The Help seems to state that choosing Data > Calculate > Recalculate (or 
its equivalent shortcut F9) “recalculates the currently selected cells 
and formula cells that depend on them”. Whatever I try in Calc, these 
interactions affect lots of cells, not just those currently selected.

In an empty spreadsheet, try the following:
(a) Set Data > Calculate > AutoCalculate to off.
(b) Type =a1+1 into cell a2.
(c) Type the value 1 into cell a1.
(d) Type =e5+1 into cell e6.
(e) Type the value 1 into cell e5.
(f) Select cells e5 and e6.
(g) Choose Data > Calculate > Recalculate or press F9.
When I do this, the value in the unselected cell a2 is updated.

Is the Help inaccurate or am I muddled?

And, if my example above is valid, what does Recalculate Hard do that 
Recalculate doesn’t?

Regards,

Steve