created a simple parameter set:
object(TCA_ParameterSet)#1 (1) {
  ["elements":"TCA_ParameterSet":private]=>
  array(2) {
    [1]=>
    object(TCA_Parameter)#2 (2) {
      ["name":"TCA_Parameter":private]=>
      string(1) "1"
      ["value":"TCA_Parameter":private]=>
      string(3) "one"
    }
    [2]=>
    object(TCA_Parameter)#3 (2) {
      ["name":"TCA_Parameter":private]=>
      string(1) "2"
      ["value":"TCA_Parameter":private]=>
      string(3) "two"
    }
  }
}

created a compound parameter:
object(TCA_ParameterSet)#4 (1) {
  ["elements":"TCA_ParameterSet":private]=>
  array(1) {
    ["attributes"]=>
    object(TCA_ParameterSet)#1 (1) {
      ["elements":"TCA_ParameterSet":private]=>
      array(2) {
        [1]=>
        object(TCA_Parameter)#2 (2) {
          ["name":"TCA_Parameter":private]=>
          string(1) "1"
          ["value":"TCA_Parameter":private]=>
          string(3) "one"
        }
        [2]=>
        object(TCA_Parameter)#3 (2) {
          ["name":"TCA_Parameter":private]=>
          string(1) "2"
          ["value":"TCA_Parameter":private]=>
          string(3) "two"
        }
      }
    }
  }
}

created a 3 level parameter:
object(TCA_Parameter)#5 (2) {
  ["name":"TCA_Parameter":private]=>
  string(4) "more"
  ["value":"TCA_Parameter":private]=>
  NULL
}

set:
array(2) {
  ["level3"]=>
  array(1) {
    ["attributes"]=>
    array(2) {
      [1]=>
      string(3) "one"
      [2]=>
      string(3) "two"
    }
  }
  ["more"]=>
  NULL
}
set after deletion:
array(1) {
  ["level3"]=>
  array(1) {
    ["attributes"]=>
    array(2) {
      [1]=>
      string(3) "one"
      [2]=>
      string(3) "two"
    }
  }
}
keys: array(1) {
  [0]=>
  string(6) "level3"
}
values: array(1) {
  [0]=>
  object(TCA_ParameterSet)#4 (1) {
    ["elements":"TCA_ParameterSet":private]=>
    array(1) {
      ["attributes"]=>
      object(TCA_ParameterSet)#1 (1) {
        ["elements":"TCA_ParameterSet":private]=>
        array(2) {
          [1]=>
          object(TCA_Parameter)#2 (2) {
            ["name":"TCA_Parameter":private]=>
            string(1) "1"
            ["value":"TCA_Parameter":private]=>
            string(3) "one"
          }
          [2]=>
          object(TCA_Parameter)#3 (2) {
            ["name":"TCA_Parameter":private]=>
            string(1) "2"
            ["value":"TCA_Parameter":private]=>
            string(3) "two"
          }
        }
      }
    }
  }
}