}

    return https://urn.to/r/pkg; # NOTE: System default.
  }

  #
  # NOTE: This procedure returns the full URI to use when looking up a
  #       specific package via the package repository server.  The apiKeys
  #       argument is the list of API keys to use -OR- an empty list if a
  #       public package is being looked up.  The package argument is the
  #       name of the package being looked up, it cannot be an empty
  #       string.  The version argument is the specific version being
  #       looked up -OR- an empty string for any available version.  There
  #       are no HTTP requests issued by this procedure; it simply returns
  #       the URI to use.
  #
  proc getLookupUri { apiKeys package version } {
    set baseUri [getLookupBaseUri]

    if {[string length $baseUri] == 0} then {
      return ""
    }

    #
    # NOTE: Build the HTTP request URI using the specified query parameter
    #       values, escaping them as necessary.  Also, include the standard
    #       query parameters with constant values for this request type.
    #
    set anonymousApiKey ""

    if {[isEagle]} then {
      if {[llength $apiKeys] > 0} then {
        return [appendArgs \
            $baseUri ?raw=1&method=lookup&apiKeys= [uri escape uri \
            [join $apiKeys ,]] &package= [uri escape uri $package] \
            &version= [uri escape uri $version]]
      } else {
        return [appendArgs \
            $baseUri ?raw=1&method=lookup&apiKey= [uri escape uri \
            $anonymousApiKey] &package= [uri escape uri $package] \
            &version= [uri escape uri $version]]
      }
    } else {
      package require http 2.0

      if {[llength $apiKeys] > 0} then {
        return [appendArgs \
            $baseUri ? [::http::formatQuery raw 1 method lookup \
            apiKeys [join $apiKeys ,] package $package version \
            $version]]
      } else {
        return [appendArgs \
            $baseUri ? [::http::formatQuery raw 1 method lookup \
            apiKey $anonymousApiKey package $package version \
            $version]]
      }
    }
  }

  #
  # NOTE: This procedure returns the version of the package that should be
  #       used to lookup the associated [package ifneeded] script -OR- an
  #       empty string if no such version exists.  The package argument is

    return $result
  }

  #
  # NOTE: This procedure issues an HTTP request that should return metadata
  #       that can be used to load and/or provide the specified package.
  #       The apiKeys argument is the list of API keys to use -OR- an empty
  #       list if a public package is being looked up.  The package argument
  #       is the name of the package, it cannot be an empty string.  The
  #       version argument is the specific version being looked up -OR- an
  #       empty string for any available version.  This procedure may raise
  #       script errors.  All line-endings are normalized to Unix-style;
  #       therefore, all script signatures must assume this.
  #
  proc getLookupData { apiKeys package version } {
    variable verboseUriDownload

    set uri [getLookupUri $apiKeys $package $version]

    if {[string length $uri] == 0} then {
      return ""
    }

    if {$verboseUriDownload} then {
      pkgLog [appendArgs \

  #
  # <public>
  proc getPackageFromRepository { package version caller } {
    #
    # NOTE: Get the list of API keys and try each one, in order, until
    #       the package is found.
    #
    set apiKeys [getApiKeys]


    #
    # NOTE: Issue the non-anonymous lookup request to the remote
    #       package repository.
    #
    set data [getLookupData $apiKeys $package $version]

    #
    # NOTE: Attempt to grab the lookup code from the non-anonymous
    #       response data.
    #
    set code [getLookupCodeFromData $data]

    #
    # NOTE: If necessary, fallback with to an anonymous request.

    #
    if {![isLookupCodeOk $code]} then {
      #
      # NOTE: Issue the anonymous lookup request to the remote
      #       package repository.
      #
      set data [getLookupData [list] $package $version]

      #
      # NOTE: Attempt to grab the lookup code from the anonymous
      #       response data.
      #
      set code [getLookupCodeFromData $data]
    }

    #
    # NOTE: Attempt to grab the lookup data from the response data.
    #       Upon failure, this should contain the error message.
    #
    set result [getLookupResultFromData $data]