ACCEPT --> <variable-ref> -+-+------------------------------+-+->
                             | +-> DEFAULT <default-value> ---+ |
                             | +-> HIDE ----------------------+ |
                             | +-> PROMPT <string-literal> ---+ |
                             | +-> NOPROMPT ------------------+ |
                             | +-> TIMEOUT <numeric-literal> -+ |
                             | +-> UPPER ---------------------+ |
                             +-------------- <------------------+

  variable-ref =

  --+-----+---> identifier -+--------------------------------+->
    +> : -+                 +-+-------------+-> : identifier +
                              +> INDICATOR -+