I'm trying to understand what Word sets as accumulated spacing between two lines, where there is an AFTER setting on line 1 (upper line), followed by a BEFORE setting on line 2 (located below line 1).

The results are not what I expected

These two combinations produced the same spacing between lines:
LINE 1 AFTER = 6pt
LINE 2 BEFORE = 12pt
RESULT (looks like double spacing)

LINE 1 AFTER = 0pt
LINE 2 BEFORE = 12pt
RESULT (looks like double spacing)

I assume from this that Word defaults to the greater of the two settings.
Is that correct?
Thanks in advance