# Namespaces in AL (Business Central)

_Published: 2023-12-28 · Author: Finn_

## Namespaces in AL

[Microsoft Learn: Namespaces in AL](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-namespaces-overview)

The purpose of this article is to show you how Namespaces can help you organize your code and make it more readable and more maintainable.

## Naming Namespaces and Nested Namespaces

### Syntax

Put the following line as the first line in all your AL files in your project.

````al
namespace MyNamespace.MyNestedNamespace;
````

I use my company name `FinnPedersenFrance` as the Namespace.

Deciding on which Nested Namespaces you need is a bit more complicated. It really depends on your specific situation.

First of all, it is not mandatory to have a Nested Namespace, but I think most cases call for one or two levels. Erik Hougaard suggests having a group level at first: Like `Apps` or `Tools`, which is also what I have done in the following examples.

Without the group level

````al
namespace FinnPedersenFrance.BasicSubscriptionManagement;
using FinnPedersenFrance.Library;
````

With the group level `App` and `Tools` nested Namespaces.

````al
namespace FinnPedersenFrance.App.BasicSubscriptionManagement;
using FinnPedersenFrance.Tools.Library;
````

I can also recommend to watch this video on YouTube [Finally we got namespaces in AL](https://www.youtube.com/watch?v=Turx8thR8LU&t=1277s) by [Erik Hougaard](https://www.hougaard.com/). Erik also gives his advice on how to name the Namespace and NestedNamespaces.

## Code Readability

To illustrate this, I will use a small app for selling subscriptions in Business Central. The app is an extension to Items and Blanket Sales Order.

Notice how the `using` directive tells the developer where we are in the standard application.

````al
namespace FinnPedersenFrance.App.BasicSubscriptionManagement;
using Microsoft.Inventory.Item;

tableextension 50140 "Subscription Item" extends Item
````

````al
namespace FinnPedersenFrance.App.BasicSubscriptionManagement;
using Microsoft.Inventory.Item;
using Microsoft.Sales.Document;
using FinnPedersenFrance.Tools.Library;

codeunit 50144 "Test Subscription App"
````

## The fully qualified name

When should you use the `using` directive and when should you use the fully qualified name?

In the `Codeunit "Subscription Management"` below, I declare `using Microsoft.Sales.Document` and `using Microsoft.Inventory.Item`, but I choose to fully qualify the variable `Codeunit System.Automation."Approvals Mgmt.";`. Why? Because the `ApprovalsMgmt` variable is only used locally in the `MakeOrderYN` function. Where the **theme** of the Codeunit is **Sales Document** and the **Inventory Item**. I hope it makes sense.

You basically don't need to know in the top of the Codeunit that I am calling a function from the `System.Automation` once.

````al
namespace FinnPedersenFrance.App.BasicSubscriptionManagement;

using Microsoft.Sales.Document;
using Microsoft.Inventory.Item;

codeunit 50140 "Subscription Management"

    procedure MakeOrderYN(SalesHeader: Record "Sales Header")
    var
        ApprovalsMgmt: Codeunit System.Automation."Approvals Mgmt.";
    begin
        if ApprovalsMgmt.PrePostApprovalCheckSales(SalesHeader) then
            Codeunit.Run(Codeunit::"Blnkt Sales Ord. to Ord. (Y/N)", SalesHeader);
    end;
````

In the above code, the following variable declaration uses the fully qualified name `Codeunit System.Automation."Approvals Mgmt."`.

````al
    var
        ApprovalsMgmt: Codeunit System.Automation."Approvals Mgmt.";
````

Where the `Record "Sales Header"` is not fully qualified, because we have already declared using the `Microsoft.Sales.Document` namespace which includes the Record definition.  

````al
procedure MakeOrderYN(SalesHeader: Record "Sales Header")
````

You have to find the right balance and your guide is the readability of the code. Does it make the code easier to read? I think the above example illustrates this quite well.

In this example, you could question if the `.App` is needed in the Namespace declaration, but it depends on the context.

## How does Microsoft use Namespaces?

I started by saying that Namespaces is to make the code more readable. So let us take a look at how Microsoft is using Namespaces.

Below is the first lines of Table 18 Customer.

I have two observations to this.

- First of all, it is not really more readable because Microsoft declares the `using` directive everywhere. This is the easy way of implementing Namespaces. No thinking needed.  
- Second. However, Microsoft has made an effort in choosing good names for the Namespaces and Nested Namespaces and we can use this as a source of inspiration.

### First level

- `Microsoft`
- `System`

It is a bit confusing. Why not just one? `Microsoft`

How will you choose where to look for a utility?

````al
using Microsoft.Utilities;
using System.Utilities;
````

I recommend using the first level to name the owner of the code.

### Second level

The second level is typically split into application areas or tools.

Application Area or Product

- `Bank`
- `Finance`
- `Sales`

Tools

- `Foundation`
- `Utilities`

or none

- `using System;`

Not having a second level here, seems inconsistent. What function would qualify for being at a top level?

### Third and Fourth level

The third level is an area and the fourth level is a feature.
You could discuss whether a fourth level is needed, but maybe the size of the feature justifies the need for the extra level.

````al
using Microsoft.Finance.Currency;
using Microsoft.Finance.Dimension;
using Microsoft.Finance.GeneralLedger.Journal;
using Microsoft.Finance.GeneralLedger.Setup;
````

### Table 18 Customer

As it looked in version 23.

I recommend that you avoid having such a long using declaration.
Find the right balance. Consider what is the theme of your object and then use fully qualified variable declarations where it makes sense.

````al
namespace Microsoft.Sales.Customer;

using Microsoft.Bank.BankAccount;
using Microsoft.Bank.DirectDebit;
using Microsoft.CRM.BusinessRelation;
using Microsoft.CRM.Campaign;
using Microsoft.CRM.Contact;
using Microsoft.CRM.Outlook;
using Microsoft.CRM.Setup;
using Microsoft.CRM.Team;
using Microsoft.EServices.OnlineMap;
using Microsoft.Finance.Currency;
using Microsoft.Finance.Dimension;
using Microsoft.Finance.GeneralLedger.Journal;
using Microsoft.Finance.GeneralLedger.Setup;
using Microsoft.Finance.ReceivablesPayables;
using Microsoft.Finance.SalesTax;
using Microsoft.Finance.VAT.Registration;
using Microsoft.Finance.VAT.Setup;
using Microsoft.Foundation.Address;
using Microsoft.Foundation.Calendar;
using Microsoft.Foundation.Comment;
using Microsoft.Foundation.Enums;
using Microsoft.Foundation.NoSeries;
using Microsoft.Foundation.PaymentTerms;
using Microsoft.Foundation.Period;
using Microsoft.Foundation.Reporting;
using Microsoft.Foundation.Shipping;
using Microsoft.Integration.Dataverse;
using Microsoft.Integration.Graph;
using Microsoft.Intercompany.Partner;
using Microsoft.Inventory.Intrastat;
using Microsoft.Inventory.Item.Catalog;
using Microsoft.Inventory.Location;
using Microsoft.Inventory.Tracking;
using Microsoft.Pricing.Calculation;
using Microsoft.Pricing.PriceList;
using Microsoft.Pricing.Source;
using Microsoft.Projects.Project.Job;
using Microsoft.Purchases.Vendor;
using Microsoft.Sales.Archive;
using Microsoft.Sales.Document;
using Microsoft.Sales.FinanceCharge;
using Microsoft.Sales.History;
using Microsoft.Sales.Pricing;
using Microsoft.Sales.Receivables;
using Microsoft.Sales.Reminder;
using Microsoft.Sales.Setup;
using Microsoft.Service.Contract;
using Microsoft.Service.Document;
using Microsoft.Service.Item;
using Microsoft.Service.Ledger;
using Microsoft.Service.Setup;
using Microsoft.Utilities;
using System;
using System.Automation;
using System.Email;
using System.Globalization;
using System.IO;
using System.Reflection;
using System.Security.User;
using System.Utilities;

table 18 Customer
````

## Clean AL Code Initiative

- Part 1: [Rulesets in Business Central](/programming/2023/10/10/BC-Rulesets.html)
- **Part 2**: [Namespaces in AL](/programming/2023/12/28/Namespaces-in-AL.html)
- Part 3: [VS Code Extensions for AL](/programming/2023/12/29/Extensions-for-AL.html)
- Part 4: [Automated Tests in AL](/programming/2024/01/03/Automated-Tests-in-AL.html)
- Part 5: [Advanced CodeCop Analyzer and Custom Rulesets](/programming/2024/01/05/BC-Advanced-Rulesets.html)
- Part 6: [How to make a code review](/programming/2024/01/11/how-to-make-a-code-review.html)
- Part 7: [Preconditions and TryFunctions in AL](/programming/2024/01/12/TryFunctions-in-AL.html)
- Part 8: [There is a new sheriff in town](/programming/2026/07/22/there-is-a-new-sheriff-in-town.html)

## Super fast tests covering 100% of your code

- Part 1: [Environment Interfaces - Part 1 - System Environment](/programming/2025/06/26/environment-interface-part-1.html)
- Part 2: [Environment Interfaces - Part 2 - External API](/programming/2025/06/26/environment-interface-part-2.html)
- Part 3: [Environment Interfaces - Part 3 - Standard Application](/programming/2025/06/26/environment-interface-part-3.html)
- Part 4: [Temporary Tables in Tests](/programming/2025/06/26/temporary-tables-in-tests.html)

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