CONNECT --+
  +---------+
  +-+---------------------------------------+--+
    +-> TO --+-> <connect-string-literal> --+  |
             +-> <connect-parameter> -------+  |
             +-> <connect-parameter-marker> +  |
  +--------------------------------------------+
  +-+---------------------------------------+--+
    +-> AS --> runtime-options (1) ---------+  |
  +--------------------------------------------+
  +-+-----------------------------+------------+
    +->  user-authentication  ----+            |
  +--------------------------------------------+
  ++------------------------------------------+-+
   ++-+-> CATALOG --> runtime-options (2) +-+-+ |
    | +-> SCHEMA ---> runtime-options (3) + |   |
    +--------------- , <--------------------+   |
  +---------------------------------------------+
  +-+---------------------------------------+--->
    +-> NAMES runtime-options (4) ----------+

  user-authentication =

  --> USER  -+-> '<username>' --+---+-----------------------------+-->
             +->  parameter  ---+   +-> USING -+- '<password>' +--+
                                               +-> parameter --+

  connect-string-literal =

  --> ' --> connect-expression --> ' -->

  connect-expression =

  ---+--> DEFAULT ------------+->
     ++-> db-specification -+-+
      +-------- , <---------+

  db-specification =

  -+-+-> ALIAS <alias> ---------------------------------------+
   | |  +----------------- <----------------------------------+
   | |  +-+-------------------------------------------------------+-+-+->
   | |    +-> FILENAME 'attach-spec' -+-+----------------------+--+ | |
   | |    +-> PATHNAME <path-name> ---+ +-> literal-user-auth -+    | |
   | |                                                              | |
   | +-> ATTACH attach-expression ----------------------------------+ |
   +--------------------------------, <-------------------------------+

  literal-user-auth =

  ---> USER '<username>' -+------------------------+-->
                          +-> USING '<password>'  -+

  attach-expression =

  -+------------------++-> FILENAME -> '<attach-spec>' -+-+
   +-> ALIAS <alias> -++-> PATHNAME ->  <path-name> ----+ |
   +------------------------------------------------------+
   ++------------------------+----------------------------+
    +--> literal-user-auth --+                            |
   +------------------------------------------------------+
   ++-----------------------------+------------------------>
    +-+-+-> database-options --+-++
      | +-> attach-options ----+ |
      +----------- <-------------+

  attach-spec =

  --+----------------+-> <file-spec> ----->
    +-> <node-spec> -+

  node-spec =

  -+-> <nodename> -+-------------------+-+->
   |               +-> <access-string> + |
   +------------------ :: <--------------+

  access-string =

  -+-> " <user-name> <password> " --+->
   +-> " <VMS-proxy-user-name> " ---+

  database-options =

  --+--> ELN ---------------------+-->
    +--> NSDS --------------------+
    +--> rdb-options -------------+
    +--> VIDA --------------------+
    +--> VIDA V1 -----------------+
    +--> VIDA V2 -----------------+
    +--> VIDA V2N ----------------+
    +--> NOVIDA ------------------+
    +--> DBIV1 -------------------+
    +--> DBIV31 ------------------+
    +--> DBIV70 ------------------+

   rdb-options =

   -+-> RDBVMS --+-->
    +-> RDB030 --+
    +-> RDB031 --+
    +-> RDB040 --+
    +-> RDB041 --+
    +-> RDB042 --+
    +-> RDB050 --+
    +-> RDB051 --+
    +-> RDB060 --+
    +-> RDB061 --+
    +-> RDB070 --+
    +-> RDB071 --+

  attach-options =

  -+-> DBKEY -+-> SCOPE IS -+-> ATTACH -------+----+->
   +-> ROWID -+             +-> TRANSACTION --+    |
   +-> MULTISCHEMA IS -+-> ON --+------------------+
   |                   +-> OFF -+                  |
   +-> PRESTARTED TRANSACTIONS ARE -+-> ON --+-----+
   |                                +-> OFF -+     |
   +-+-------+-> RESTRICTED ACCESS ----------------+
   | +-> NO -+                                     |
   +-> DISPLAY CHARACTER SET <character-set-name> -+

  runtime-options

  --+---> 'string-literal' ------+----->
    +---> parameter -------------+
    +---> parameter-marker ------+