17.7. Operator request query description of the prepared operator

  <describe statement> :: =
   <describe input statement>
 |  <describe output statement>
 <describe input statement> :: =
    DESCRIBE INPUT <SQL statement name> <using descriptor>
 <describe output statement> :: =
    DESCRIBE [OUTPUT] <SQL statement name> <using descriptor>
 <using clause> :: = <using arguments> |  <using descriptor>
 <using arguments> :: =
  {USING |  INTO} <argument> [{<comma> <argument>} ...]
 <argument> :: = <target specification>
 <using descriptor> :: =
  {USING |  INTO} SQL DESCRIPTOR <descriptor name>
 <target specification> :: =
   <parameter specification>
 |  <variable specification>
 <parameter specification> :: =
   <parameter name> [<indicator parameter>]
 <indicator parameter> :: = [INDICATOR] <parameter name>
 <variable specification> :: =
   <embedded variable name> [<indicator variable>]
 <indicator variable> :: = [INDICATOR] <embedded variable name> 

Comment:

When the DESCRIBE statement is executed, the descriptor specified in the statement descriptor is filled with information describing either the result of a previously prepared SQL statement (if it is a select statement) or the number and types of parameters of the prepared statement. In <using descriptor> here it is supposed to write USING SQL DESCRIPTOR.