#
    variable forceSecureUri; # DEFAULT: true

    if {$force || ![info exists forceSecureUri]} then {
      set forceSecureUri true
    }

    #
    # NOTE: Should the HTTP request processor fail if the "tls" package is
    #       not available?
    #
    variable mustHaveTls; # DEFAULT: true

    if {$force || ![info exists mustHaveTls]} then {
      set mustHaveTls true
    }

    #
    # NOTE: Is this HTTP request processor allowed to use plain HTTP if/when
    #       the "tls" package is not available?  This should only be changed
    #       if the "tls" package cannot be easily installed for use with the
    #       native Tcl interpreter in use.  It should be noted here that the
    #       official package repository server reserves the right to refuse
    #       plain HTTP connections, which means that changing this setting

    #
    # NOTE: This variable is used to determine if plain HTTP URIs should be
    #       converted to HTTPS, if the "tls" package is available.
    #
    variable forceSecureUri

    #
    # NOTE: This variable is used to determine if an error should be raised
    #       if the "tls" package is not available.
    #
    variable mustHaveTls

    #
    # NOTE: This variable is used to determine if plain HTTP is allowed if
    #       the "tls" package is not available.
    #
    variable allowInsecureUri

    #

    #
    if {[info exists tcl_version] && $tcl_version >= 8.6} then {
      namespace eval ::tcl::unsupported {}
      set ::tcl::unsupported::socketAF inet
    }

    #
    # NOTE: Setup lowercase URI scheme prefixes used within this procedure
    #       to detect and/or change the URI scheme used.  By default, this
    #       procedure will always attempt to force HTTPS use when the "tls"
    #       package is available -AND- it disallows redirects from HTTPS to
    #       HTTP -AND- it disallows using HTTP when the "tls" package is
    #       unavailable.
    #
    set http http://; set https https://

    #
    # NOTE: If the "tls" package is available, always attempt to use HTTPS;
    #       otherwise, only attempt to use HTTP if explicitly allowed.
    #
    if {[catch {package require tls} error] == 0} then {
      ::http::register https 443 [list ::tls::socket -tls1 true]

      if {$forceSecureUri} then {
        if {[string tolower [string range $uri 0 6]] eq $http} then {
          set uri [appendArgs $https [string range $uri 7 end]]
        }
      }
    } else {
      if {$mustHaveTls} then {
        error [appendArgs \
            "the \"tls\" package cannot be loaded: " $error]
      }

      if {$allowInsecureUri} then {
        if {[string tolower [string range $uri 0 7]] eq $https} then {
          set uri [appendArgs $http [string range $uri 8 end]]
        }
      }
    }

    #
    # NOTE: Unless the caller forbids it, display progress messages during
    #       the download.

            #
            # NOTE: For security, by default, do NOT follow an HTTP
            #       redirect if it attempts to redirect from HTTPS
            #       to HTTP.
            #
            if {!$allowInsecureRedirect && \
                [string tolower [string range $uri 0 7]] eq $https && \
                [string tolower [string range $location 0 7]] ne $https} then {
              #
              # NOTE: Just "give up" and raise a script error.
              #
              ::http::cleanup $token; error [appendArgs \
                  "refused insecure redirect from \"" $uri "\" to \"" \
                  $location \"]
            }