DECLARE -+-> :<variable-name> +--+---------------+-+
           +-------- , <--------+  +--> CONSTANT --+ |
                                   +--> UPDATABLE -+ |
  +--------------------------------------------------+
  +-+-> data-type ----+-+--------------------+------->
    +-> <domain-name> + +-> default-clause  -+

  default-clause =

  --+-> DEFAULT --+--+--> date-time-literal -+----->
    +->   = ------+  +--> interval-literal  -+
                     +--> numeric-literal  --+
                     +--> string-literal  ---+
                     +--> : <variable-name> -+