lappend ::auto_path [file join $pkgr_path Eagle1.0]
    } else {
      lappend ::auto_path [file join [file dirname [file dirname \
          [file dirname $pkgr_path]]] externals Eagle lib Eagle1.0]
    }
  }

  variable pkgr_harpy_path; # DEFAULT: <unset>

  if {![info exists pkgr_harpy_path]} then {
    set pkgr_harpy_path [file normalize [file dirname [info script]]]

    if {![file isfile [file join $pkgr_harpy_path sign.eagle]]} then {
      set pkgr_harpy_path [file join [file dirname [file dirname \
          [file dirname $pkgr_harpy_path]]] externals Harpy Tools]
    }
  }

  #
  # NOTE: This package requires several packages from the Eagle core script
  #       library, even when it is being used by native Tcl.  If necessary,
  #       prior to evaluating this file in native Tcl, its auto-path should
  #       be modified to include an "Eagle1.0" directory (i.e. a directory
  #       containing the Eagle core script library files "auxiliary.eagle",
  #       "file1.eagle", and "platform.eagle").

      } else {
        error "cannot sign with OpenPGP: passphrase file does not exist"
      }
    } else {
      error "cannot sign with OpenPGP: passphrase file is not configured"
    }
  }

  #
  # NOTE: This procedure attempts to create a Harpy (script) certificate for
  #       the specified (named) file.  Non-zero is only returned if the Harpy
  #       (script) certificate is created successfully.  A script error should
  #       not be raised by this procedure.  The fileName argument must be the
  #       fully qualified path and file name of the file to be signed.  This
  #       procedure assumes that the Harpy package for Eagle is installed and
  #       ready for use (i.e. it can find a valid license certificate).
  #
  # <internal>
  proc createHarpyCertificate { fileName } {
    variable harpySignCommand
    variable pkgr_harpy_path

    set toolFileName \
        [file nativename [file join $pkgr_harpy_path sign.eagle]]

    set scriptFileName [file nativename $fileName]
    set vendor "Mistachkin Systems"; # NOTE: System default.

    if {[isEagle]} then {
      set shellFileName [formatExecArgument [info nameofexecutable]]
      set toolFileName [formatExecArgument $toolFileName]
      set scriptFileName [formatExecArgument $scriptFileName]
      set vendor [formatExecArgument $vendor]

      if {[catch {
        eval exec -success Success [subst $harpySignCommand]
      }] == 0} then {
        return true
      }
    } else {
      #
      # HACK: Make sure that Eagle is loaded into this process so that we
      #       can figure out the shell for it and then [exec] out to that
      #       shell.
      #
      makeEagleReady

      set shellFileName [eagle {
        file join [file dirname [lindex [info assembly] end]] EagleShell.exe
      }]

      if {[catch {
        eval exec [subst $harpySignCommand] 2>@1
      } result] == 0} then {
        return true
      }
    }

    return false
  }

  #
  # NOTE: This procedure attempts to create an OpenPGP signature for the
  #       specified (named) file.  Non-zero is only returned if the OpenPGP
  #       signature is created successfully.  A script error should not be
  #       raised by this procedure.  The fileName argument must be the fully
  #       qualified path and file name of the file to be signed.

  }

  #
  # NOTE: This procedure is designed for Eagle.  It attempts to load the
  #       "best" native Tcl library.  It may raise any number of script
  #       errors.  There are no arguments.
  #
  # <internal>
  proc makeTclReady {} {
    #
    # NOTE: This procedure is useless when running in native Tcl; therefore,
    #       forbid its use there.
    #
    if {![isEagle]} then {
      error "already running in Tcl language"

  }

  #
  # NOTE: This procedure, which may only be used from a native Tcl script,
  #       checks if Garuda and Eagle are loaded and ready.  If not, a script
  #       error is raised.  There are no arguments.
  #
  # <internal>
  proc eagleMustBeReady {} {
    #
    # NOTE: This procedure is useless when running in Eagle; therefore,
    #       forbid its use there.
    #
    if {[isEagle]} then {
      error "already running in Eagle language"

  }

  #
  # NOTE: This procedure is designed for native Tcl.  It attempts to load
  #       the Garuda package and gain access to Eagle.  It may raise any
  #       number of script errors.  There are no arguments.
  #
  # <internal>
  proc makeEagleReady {} {
    #
    # NOTE: This procedure is useless when running in Eagle; therefore,
    #       forbid its use there.
    #
    if {[isEagle]} then {
      error "already running in Eagle language"

      append openPgpSignCommand {gpg2 --detach-sign --armor}

      append openPgpSignCommand \
          { --passphrase-file [formatExecArgument [getOpenPgpPassphraseFile]]}

      append openPgpSignCommand { --batch --yes {${fileName}}}
    }

    #
    # NOTE: The command to use when creating Harpy signatures for downloaded
    #       package scripts.
    #
    variable harpySignCommand; # DEFAULT: {${shellFileName}} -file ...

    if {![info exists harpySignCommand]} then {
      set harpySignCommand ""

      append harpySignCommand {{${shellFileName}}}
      append harpySignCommand { -noArgumentsFileName -file {${toolFileName}}}
      append harpySignCommand { {${scriptFileName}} {${vendor}}}
    }

    #
    # NOTE: Verify that the package script matches the current language
    #       when called from the [package unknown] handler?
    #
    variable strictUnknownLanguage; # DEFAULT: true