Library /sys$common/syshlp/basichelp.hlb Run time errors, ECHTYPNOT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Prompt/echo type not supported (ERR=256)

  The specified prompt or echo type is invalid.  BASIC supports only the
  default prompt and echo types.  Do not change the prompt or echo type.
  If you do so, you should continue to  use  direct  calls  to  VAX  GKS
  routines rather than use BASIC input statements.