'Nastaveni:
Dim areaPropertyName As String = "Plocha" ' Nazev uzivatelske iVlastnosti
Dim createMissingProperty As Boolean = False ' Vytvorit chybejici iVlastnost
Dim valueFormat As String = "0.##" ' Presnost hodnoty na dve desetinna mista
Dim conversionConstant As Double = 10 * 10 ' Prevodni konstanta jednotek cm2 => mm2

'ThisDoc.Document musi byt soucast
Dim partDoc As PartDocument = ThisDoc.Document

Dim area As Double = partDoc.ComponentDefinition.MassProperties.Area
area = area * conversionConstant

Dim userDefinedProperties As PropertySet = partDoc.PropertySets("{D5CDD505-2E9C-101B-9397-08002B2CF9AE}")

Dim areaProperty As [Property]
Try
    areaProperty = userDefinedProperties(areaPropertyName)
Catch
    If createMissingProperty Then
        areaProperty = userDefinedProperties.Add("", areaPropertyName)
    Else
        Return
    End If
End Try


Dim areaString As String = area.ToString(valueFormat)
If areaProperty.Value.ToString() <> areaString Then
    areaProperty.Value = areaString
End If