V7

class hotel_room_amenities_type(osv.osv):

_name = 'hotel.room_amenities_type'

_description = 'amenities Type'

_inherits = {'product.category':'cat_id'}

_columns = {

'cat_id':fields.many2one('product.category', 'category', required=True, ondelete='cascade'),

}

_defaults = {

'isamenitype': lambda * a: 1,

}

class product_category(osv.osv):

_inherit = "product.category"

_columns = {

'isroomtype':fields.boolean('Is Room Type'),

'isamenitype':fields.boolean('Is amenities Type'),

'isservicetype':fields.boolean('Is Service Type'),

}

product_category()

V8

class HotelRoomAmenitiesType(models.Model):  
 _name = 'hotel.room.amenities.type'    _description = 'amenities Type'  
 cat_id = fields.Many2one('product.category', 'category', required=True,                             delegate=True, ondelete='cascade')