Administration > Environment Variables > APTTBLCELLMARGB — Specifying the Default Bottom Margin for Table Cells
  
APTTBLCELLMARGB — Specifying the Default Bottom Margin for Table Cells
Specifies the default bottom table cell margin used in published output. The margins can also be set on a table-by-table basis using the Table Properties dialog box; these settings will override the values specified by the environment variable. The margins are measured in points and must be specified with an integer.