Y must be a simple numeric scalar or vector containing one or more of the values for name-class. See also Name Classification .

X is optional. If present, it must be a simple character scalar or vector. R is a list of the names of active objects whose name-class is included in Y in standard sorted order.

If any element of Y is negative, positive values in Y are treated as if they were negative, and R is a vector of character vectors. Otherwise, R is simple character matrix.

Furthermore, if ⎕NL is being evaluated inside the namespace associated with a Class or an Instance of a Class, and any element of Y is negative, R includes the Public names exposed by the Base Class (if any) and all other Classes in the Class hierarchy.

If X is supplied, R contains only those names which begin with any character of X. Standard sorted order is in Unicode point order for Unicode editions, and in the collation order of ⎕AV for Classic editions.

If an element of Y is an integer, the names of all of the corresponding sub-name-classes are included in R. For example, if Y contains the value 2, the names of all variables (name-class 2.1), fields (2.2), properties (2.3) and external or shared variables (2.6) are obtained. Otherwise, only the names of members of the corresponding sub-name-class are obtained.

Examples:

      ⎕NL 2 3
A
FAST
FIND
FOO
V

      'AV' ⎕NL 2 3
A
V

      ⎕NL ¯9
 Animal  Bird  BirdBehaviour  Coin  Cylinder  DomesticParrot  Eeyore  FishBehaviour  Nickel  Parrot  Penguin  Polly  Robin 
      ⎕NL ¯9.3 ⍝ Instances
 Eeyore  Nickel  Polly  Robin 
      ⎕NL ¯9.4 ⍝ Classes
 Animal  Bird  Coin  Cylinder  DomesticParrot  Parrot  Penguin
      ⎕NL ¯9.5 ⍝ Interfaces
 BirdBehaviour  FishBehaviour

⎕NL can also be used to explore Dyalog GUI Objects, .NET types and COM objects.

Dyalog GUI Objects

⎕NL may be used to obtain lists of the Methods, Properties and Events provided by Dyalog APL GUI Objects.

      'F' ⎕WC 'Form'
      F.⎕NL -2 ⍝ Properties
 Accelerator AcceptFiles  Active  AlphaBlend  AutoConf  Border  BCol  Caption ...

      F.⎕NL -3 ⍝ Methods
 Animate  ChooseFont  Detach  GetFocus  GetTextSize  ShowSIP  Wait

      F.⎕NL -8 ⍝ Events
Close  Create  DragDrop  Configure  ContextMenu  DropFiles  DropObjects  Expose  Help ...

.NET Classes (Types)

⎕NL can be used to explore .NET types.

When a reference is made to an undefined name, and ⎕USING is set, APL attempts to load the Type from the appropriate .NET Assemblies. If successful, the name is entered into the symbol table with name-class 9.6.

      ⎕USING←'System'
      DateTime
(System.DateTime)
      ⎕NL -9
 DateTime
      ⎕NC,⊂'DateTime'
9.6

The names of the Properties and Methods of a .NET Type may then be obtained using ⎕NL.

      DateTime.⎕NL -2 ⍝ Properties
 MaxValue  MinValue  Now  Today  UtcNow 

      DateTime.⎕NL -3 ⍝ Methods
 get_Now  get_Today  get_UtcNow  op_Addition  op_Equality  ...

In fact it is not necessary to make a separate reference first, because the expression Type.⎕NL (where Type is a .NET Type) is itself a reference to Type. So, (with ⎕USING still set to 'System'):

      Array.⎕NL -3
 BinarySearch  Clear  Copy  CreateInstance  IndexOf  LastIndexOf  Reverse  Sort

      ⎕NL -9
 Array  DateTime

      ⎕USING←'System.Windows.Forms,system.windows.forms.dll'

      FormBorderStyle.⎕NL -2
Fixed3D  FixedDialog  FixedSingle  FixedToolWindow  None  Sizable  SizableToolWindow 

      FormBorderStyle.FixedDialog.value__
3

      FormBorderStyle.({⍵,[1.5]⍎¨⍵,¨⊂'.value__'}⎕NL -2)
 Fixed3D            2
 FixedDialog        3
 FixedSingle        1
 FixedToolWindow    5
 None               0
 Sizable            4
 SizableToolWindow  6

      xl←⎕NEW'OLEClient'(⊂'ClassName' 'Excel.Application')

      xl.⎕NL -2 ⍝ Properties
 _Default  ActiveCell  ActiveChart  ActiveDialog  ActiveMenuBar  ActivePrinter  ActiveSheet  ActiveWindow ...

      xl.⎕NL -3 ⍝ Methods
 _Evaluate  _FindFile  _Run2  _Wait  _WSFunction  ActivateMicrosoftApp  AddChartAutoFormat  AddCustomList  Browse  Calculate ...

      ⎕NL -9
 xl