Report:Fields: read-only: array
  The columns definition in form of:
  Fields:={}
  AAdd( Field, {cTitle,cField,cPicture,lTotal,cSubTotal} )
  ...
  Where:
  cTitle    - is column heading
  cField    - is a full name of database field (alias->field).
  cPicture  - is a picture mask definition for this field
  lTotal    - is true if the field should be totaled
  cSubTotal - is the database filed name after which we shall total or ""