def __init__(self, layer):
        self.layer = layer
        self.template = loader.get_template(
            'regulations/layers/definition_citation.html')
        self.sectional = False
        self.version = None
        self.rev_urls = SectionUrl()
        self.rendered = {}
        # precomputation
        for def_struct in self.layer['referenced'].values():
            def_struct['reference_split'] = def_struct['reference'].split('-')