Isometric material list column width

Dear sirs,

How the Isometric material list column width is calculated?

My und file is as follows:

MatlistFile "matl" APPEND with 30 lines
MatControl OFF
MaterialList ON
MaterialList DRWG
MaterialList RIGHT DESCRIPTION
MaterialList Charheight 2mm Lspacing 100
MaterialList Code 29 DUMMY SINGLE
MaterialList PartNumbers GENERATED
MaterialList GRIDLINES ON
MaterialList TRUNNIONPLATECATEGORY FITTING
MaterialList TableDefinition Column 1 PARTNUMBER with Width 6
Column 2 DESCRIPTION with Width 80
Column 3 BORE with Width 7
Column 4 QUANTITY in Metres with Width 7

The total column width is 6+80+7+7=100

But the total width is 179.4mm in dwg file, why?