How paragraphSpaceBefore and paragraphSpaceAfter works?

7.4.6. paragraphSpaceBefore attribute Specifies the space before a paragraph. Adjacent vertical space collapses. For two adjoining paragraphs (A and B), where A has paragraphSpaceAfter 12 and B has paragraphSpaceBefore 24, the total space between the paragraphs will be 24, the maximum of the two, and not 36, the sum. If the paragraph comes at the top of the column, no extra space is left before it. Valid values range from 0 to 8000.

7.4.7. paragraphSpaceAfter attribute Specifies the space after a paragraph. Adjacent vertical space collapses. For example, for two adjacent paragraphs one having a space after and the other having a space before, the space will be the maximum of the two spaces, not the sum. No “space after” is necessary if the paragraph falls at the bottom of the  element. Valid values range from 0 to 8000.

If you think it does not act the same way as the description above, please show me your sample code. Thanks!