/sys$common/syshlp/helplib.hlb PIPE, Qualifiers, /TRUSTED  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /TRUSTED
       /NOTRUSTED

    Indicates that the PIPE command input originates in a trusted
    command procedure. PIPE commands are not allowed in CAPTIVE
    accounts. The /TRUSTED qualifier provides a way for properly
    written captive command procedures to perform PIPE operations
    when the command input originates in the captive command
    procedure where it can be trusted. For more information about
    trusted command procedures, refer to the OpenVMS Guide to System
    Security.