'Constructor
@param link: the name of the link table
@param component: the name of the component table
@param autocomplete: name of the autocomplete field
@param link_filter: filter expression to filter out records
in the component that are already linked
to the main record
@param select_existing: allow the selection of existing
component records from the registry'

def __init__(self, link=None, component=None, autocomplete=None, link_filter=None, select_existing=True):

    self.link = link
    self.component = component
    self.autocomplete = autocomplete
    self.select_existing = select_existing
    self.link_filter = link_filter
