index_storage

index_storage 
      ::= 
      ( "pctfree" n ) 
      | ( "initrans" n ) | ( "maxtrans" n ) 
      | ( "tablespace" tablespace_name ) 
      | ( "storage" "(" storage_spec { storage_spec } ")" ) 
      | ( "nosort" ) 

This rule is called by

create_index
def_column_constraint
def_table_constraint
enable_spec