The Data Rule definition has a few properties and list of columns of the table to be populated or scrambled.
There are properties:

• Row Count
• Table Name
• Insertion Mode
• Transaction Size
• Fields

Example:

 Rule Type="data"
  Table Name="dbo.CustomerDemographics"
  Rowcount Records="25"
  TransactionSize="500"
  InsMode="replace"
  Fields
   Field Name="CustomerTypeID"
    DataType Code="-8" Name="nchar" length="10"
    Pattern="$Unique($RString(1,10,5,0,0))"
   Field Name="CustomerDesc"
    DataType Code="-10" Name="ntext"
    Pattern="$IfR(10,\NULL,$RString(1,4096,5,0,0))"