Merge origin/main into community contribution

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

microsoft/knowledge/style/al-build-output-must-not-pollute-project-root.md

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+---
+bc-version: [all]
+domain: style
+keywords: [build, output, alpackages, artifact-hygiene, outfolder, project-root]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Write AL Build Artifacts to an Intentional Output Location
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+An AL project's compiled `.app` file can be written to the project root by default, and current tooling explicitly supports choosing a different destination instead — `ALTool`'s `--outfolder` option and the `al_build` agent tool's `outputPath` parameter both exist for this. The problem this rule addresses is not that root-level output is technically invalid; it is agents leaving generated `.app` files scattered through arbitrary source locations, or treating a compiled artefact as if it were part of the source tree (committing it, editing around it, referencing it as a dependency by hand).
+
+## Best Practice
+
+Write build artifacts to a deliberate, dedicated output location — configured via the build tool actually in use (e.g. `ALTool --outfolder`, or an explicit `outputPath` on the agent build tool) — and add that folder to `.gitignore`. Treat a compiled `.app` as a build artifact, never as a source file to commit or hand-edit around.
+
+## Anti Pattern
+
+Letting `.app` files accumulate in arbitrary or unversioned locations without a deliberate output path, or committing compiled artefacts into source control alongside the AL files that produced them.

microsoft/knowledge/style/al-identifiers-english.bad.al

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+codeunit 50100 "Sales Amount Calculator"
+{
+    procedure BeregnTotalbeloeb(var Salgslinje: Record "Sales Line"): Decimal
+    var
+        Beloeb: Decimal;
+    begin
+        Salgslinje.CalcSums(Amount);
+        Beloeb := Salgslinje.Amount;
+        exit(Beloeb);
+    end;
+}

microsoft/knowledge/style/al-identifiers-english.good.al

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+codeunit 50100 "Sales Amount Calculator"
+{
+    procedure CalculateTotalAmount(var SalesLine: Record "Sales Line"): Decimal
+    var
+        TotalAmount: Decimal;
+    begin
+        SalesLine.CalcSums(Amount);
+        TotalAmount := SalesLine.Amount;
+        exit(TotalAmount);
+    end;
+}

microsoft/knowledge/style/al-identifiers-english.md

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+---
+bc-version: [all]
+domain: style
+keywords: [identifiers, naming, english, captions, translation]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Write AL Identifiers in English Only
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+All AL identifiers — variables, procedures, parameters, fields, object names, enum values, and label identifiers — must be written in English, regardless of the developer's native language. Translations are handled separately through captions, tooltips, and XLIFF files, never by writing Danish, German, or other non-English identifiers directly into AL source code. This is not a stylistic preference: the public `microsoft/BCApps` codebase, maintained by engineers of many nationalities across hundreds of thousands of lines of AL, uses exclusively English identifiers, with all localization handled via caption properties and XLIFF rather than by changing identifier names. On any multi-contributor codebase, non-English identifiers make the code unreadable to contributors who don't share that language.
+
+## Best Practice
+
+Write every identifier in English, and translate developer intent rather than transliterating it — when a requirement is described in another language, the resulting variable, procedure, and field names should still read as English. Captions and tooltips may carry target-language text in the source file, with locale translations managed through XLIFF.
+
+See sample: [`al-identifiers-english.good.al`](al-identifiers-english.good.al).
+
+## Anti Pattern
+
+Using native-language identifiers such as a Danish variable or procedure name in AL source code, relying on the fact that the code still compiles and runs correctly. This makes the code unreadable to non-native-language contributors and mixes localization concerns into source that should stay language-neutral.
+
+See sample: [`al-identifiers-english.bad.al`](al-identifiers-english.bad.al).

microsoft/knowledge/style/binary-choice-must-be-boolean.bad.al

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+table 50100 "Sales Task"
+{
+    fields
+    {
+        field(1; "No."; Code[20]) { }
+        field(10; Status; Option)
+        {
+            OptionMembers = Active,Blocked;
+        }
+    }
+}
+
+codeunit 50100 "Sales Task Check"
+{
+    procedure IsOverdue(DueDate: Date): Integer
+    begin
+        // 0 = No, 1 = Yes
+        if DueDate < Today then
+            exit(1);
+        exit(0);
+    end;
+}

microsoft/knowledge/style/binary-choice-must-be-boolean.good.al

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+table 50100 "Sales Task"
+{
+    fields
+    {
+        field(1; "No."; Code[20]) { }
+        field(10; Blocked; Boolean) { }
+    }
+}
+
+codeunit 50100 "Sales Task Check"
+{
+    procedure IsOverdue(DueDate: Date): Boolean
+    begin
+        exit(DueDate < Today);
+    end;
+}

microsoft/knowledge/style/binary-choice-must-be-boolean.md

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+---
+bc-version: [all]
+domain: style
+keywords: [boolean, option, yes-no, magic-number, variable-typing, field-typing]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Binary yes/no choices must be typed as Boolean, not Option or Integer
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+When a field or variable represents a genuine true/false state — yes/no, on/off, active/inactive, blocked/not blocked — it should be typed `Boolean`. Modeling that same predicate as an `Option`/`Enum` with two members, or as an `Integer` with two magic-number values, adds a layer of indirection a reader has to resolve before understanding the code. This is about semantics, not member count: a domain concept that currently has exactly two named alternatives — Inbound/Outbound, Debit/Credit, Buy/Sell — is not automatically a Boolean in disguise. An `Enum` can be the clearer model there, including when it needs to implement an interface, preserve an existing contract, or leave room for a future third value. The distinction is whether the domain is genuinely a stable predicate, not how many states it currently has.
+
+## Best Practice
+
+Type a field or variable as `Boolean` when the domain concept is inherently a true/false state. Do not replace a meaningful two-option domain model with a Boolean solely because it currently has two values.
+
+See sample: [`binary-choice-must-be-boolean.good.al`](binary-choice-must-be-boolean.good.al).
+
+## Anti Pattern
+
+Modeling a yes/no choice as an `Option` with two members, or as an `Integer` with magic-number values, forces every caller to remember which value means what and leaves room for a meaningless third value.
+
+See sample: [`binary-choice-must-be-boolean.bad.al`](binary-choice-must-be-boolean.bad.al).

microsoft/knowledge/style/fixed-choice-set-must-use-enum-not-integer.bad.al

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+table 50101 "Course"
+{
+    fields
+    {
+        field(1; "No."; Code[20]) { }
+        // 1 = Beginner, 2..3 = Intermediate, 4+ = Advanced
+        field(10; Difficulty; Integer) { }
+    }
+}
+
+codeunit 50100 "Course Level Helper"
+{
+    procedure LevelText(Difficulty: Integer): Text
+    begin
+        case Difficulty of
+            1:
+                exit('Beginner');
+            2, 3:
+                exit('Intermediate');
+        end;
+    end;
+}

microsoft/knowledge/style/fixed-choice-set-must-use-enum-not-integer.good.al

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+enum 50100 "Course Difficulty"
+{
+    Extensible = true;
+
+    value(0; Beginner) { }
+    value(1; Intermediate) { }
+    value(2; Advanced) { }
+}
+
+table 50101 "Course"
+{
+    fields
+    {
+        field(1; "No."; Code[20]) { }
+        field(10; Difficulty; Enum "Course Difficulty") { }
+    }
+}

microsoft/knowledge/style/fixed-choice-set-must-use-enum-not-integer.md

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+---
+bc-version: [all]
+domain: style
+keywords: [enum, option, integer, magic-number, variable-typing, field-typing]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# A fixed set of named choices must use Enum, not a raw Integer
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+When a variable or field represents a fixed set of named, mutually exclusive states — a difficulty level, a document type, a processing status — it should be typed as `Enum` (or `Option` when extending an object that still uses the legacy type). Representing that same state as a plain `Integer` and tracking the meaning of each value in a comment or in a developer's head is a magic-number anti-pattern: the compiler cannot catch an out-of-range value, and branches read as opaque numbers instead of names. This is about semantics, not member count, matching `binary-choice-must-be-boolean.md`'s own distinction: a domain concept that is genuinely a stable true/false predicate belongs in `Boolean` even if someone represents it as a two-value `Enum`, while a domain concept with exactly two current named states is not automatically a Boolean in disguise — it stays an `Enum` when the states are named alternatives rather than a yes/no flag, or when it needs to implement an interface, preserve an existing contract, or leave room for a future third value.
+
+## Best Practice
+
+Declare an `Enum` with named values and branch on the enum value, not a raw number.
+
+See sample: [`fixed-choice-set-must-use-enum-not-integer.good.al`](fixed-choice-set-must-use-enum-not-integer.good.al).
+
+## Anti Pattern
+
+Using a plain `Integer` field with the meaning of each value tracked only in a comment pushes the documentation of the states into something the compiler cannot check and a future maintainer cannot rely on.
+
+See sample: [`fixed-choice-set-must-use-enum-not-integer.bad.al`](fixed-choice-set-must-use-enum-not-integer.bad.al).

microsoft/knowledge/style/intrinsic-al-functions-must-use-modern-casing.bad.al

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+codeunit 50100 "Sales Task Notify"
+{
+    procedure NotifyUpdate(Count: Integer; CustomerNo: Code[20])
+    begin
+        MESSAGE('%1 records updated.', Count);
+
+        IF NOT CONFIRM('Delete %1?', FALSE, CustomerNo) THEN
+            EXIT;
+
+        ERROR(STRSUBSTNO('%1 must not be blank.', CustomerNo));
+    end;
+}

microsoft/knowledge/style/intrinsic-al-functions-must-use-modern-casing.good.al

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+codeunit 50100 "Sales Task Notify"
+{
+    procedure NotifyUpdate(Count: Integer; CustomerNo: Code[20])
+    begin
+        Message('%1 records updated.', Count);
+
+        if not Confirm('Delete %1?', false, CustomerNo) then
+            exit;
+
+        Error(StrSubstNo('%1 must not be blank.', CustomerNo));
+    end;
+}

microsoft/knowledge/style/intrinsic-al-functions-must-use-modern-casing.md

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+---
+bc-version: [all]
+domain: style
+keywords: [casing, intrinsic-function, built-in-function, message, error, confirm, strsubstno, legacy, c-al, pascalcase]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Intrinsic AL function calls use modern casing, not legacy ALL-CAPS
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+AL is case-insensitive, so `MESSAGE(...)`, `ERROR(...)`, `CONFIRM(...)`, and `STRSUBSTNO(...)` compile and run identically to `Message(...)`, `Error(...)`, `Confirm(...)`, and `StrSubstNo(...)`. Modern AL — Microsoft's own current samples and current reference codebases — writes intrinsic/built-in function calls in the casing Microsoft assigns to the function's declared name, typically PascalCase. This is a codebase-convention claim, not a claim about what the VS Code formatter enforces: the formatter normalizes particular syntax but is not a mechanism for recasing every intrinsic function call, so do not cite formatter behavior as the reason to follow this convention. ALL-CAPS calls are a holdover from classic C/AL and signal code that has not been modernized, even though it compiles and runs correctly. Reserved keywords such as `if`, `begin`, and `for` are a separate, already-tooled concern; intrinsic function names are identifiers, not keywords, so that tooling does not catch ALL-CAPS intrinsic function calls.
+
+## Best Practice
+
+Call intrinsic functions in their modern, PascalCase form.
+
+See sample: [`intrinsic-al-functions-must-use-modern-casing.good.al`](intrinsic-al-functions-must-use-modern-casing.good.al).
+
+## Anti Pattern
+
+ALL-CAPS intrinsic function calls trip no compiler error, but they are a reliable signal that a code block was copied from old C/AL material or outdated training content rather than written against current AL conventions.
+
+See sample: [`intrinsic-al-functions-must-use-modern-casing.bad.al`](intrinsic-al-functions-must-use-modern-casing.bad.al).

microsoft/knowledge/style/namespace-must-be-verified-from-source.bad.al

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+namespace Contoso.Extensions;
+
+using System.Performance; // guessed; never verified against the source file
+
+codeunit 50100 "Tooling Extension"
+{
+    procedure Run()
+    var
+        ToolingPage: Page "Some Tooling Page"; // guessed namespace; can still resolve against a stale or cached symbol package, then fail once checked against the object's current source or a freshly downloaded one
+    begin
+        ToolingPage.Run();
+    end;
+}

microsoft/knowledge/style/namespace-must-be-verified-from-source.good.al

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+// Verified by reading line 1 of the source file for "Some Tooling Page":
+// namespace System.Tooling;
+
+namespace Contoso.Extensions;
+
+using System.Tooling;
+
+codeunit 50100 "Tooling Extension"
+{
+    procedure Run()
+    var
+        ToolingPage: Page "Some Tooling Page";
+    begin
+        ToolingPage.Run();
+    end;
+}

microsoft/knowledge/style/namespace-must-be-verified-from-source.md

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+---
+bc-version: [all]
+domain: style
+keywords: [namespace, verification, source-of-truth, using-statement]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Resolve a namespace from the referenced object's source or symbols, never by guessing
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+Since Business Central 2024 release wave 1, Microsoft's own objects are organized under a deep `Microsoft.*` namespace tree that has been renamed and restructured repeatedly. When adding a `using` directive for an existing AL object (table, codeunit, page, enum, interface, etc.), guessing its namespace from the object's name, from an older codebase, or from general familiarity produces a statement that can look plausible and still resolve to the wrong object, or fail to resolve at all, once checked against the object's actual current namespace. The reliable sources are the object's own source file (its `namespace` declaration) or, for a dependency without accessible source, its AL symbol package — not the object's name or a remembered convention.
+
+## Best Practice
+
+When referencing an existing AL object, resolve its namespace from that object's actual source file or symbol definition — never infer or invent one from its name, functional area, or naming convention.
+
+See sample: [`namespace-must-be-verified-from-source.good.al`](namespace-must-be-verified-from-source.good.al).
+
+## Anti Pattern
+
+Writing a `using` statement from memory, from an incomplete path, or from a plausible-looking guess. It can appear correct while actually resolving to the wrong object, or fail to resolve, once checked against stale or mismatched symbols, a different build configuration, or the object's actual current source — not because the compiler and the AL Language Server apply different namespace-resolution rules; they don't.
+
+See sample: [`namespace-must-be-verified-from-source.bad.al`](namespace-must-be-verified-from-source.bad.al).

microsoft/knowledge/style/var-parameters-require-an-addressable-variable.bad.al

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+codeunit 50100 "Customer Lookup"
+{
+    procedure GetCustomerName(CustomerNo: Code[20]; var Name: Text[100])
+    var
+        Customer: Record Customer;
+    begin
+        if Customer.Get(CustomerNo) then
+            Name := Customer.Name;
+    end;
+
+    procedure Sample()
+    begin
+        GetCustomerName('10000', 'placeholder'); // compile error: literal is not addressable
+    end;
+}

microsoft/knowledge/style/var-parameters-require-an-addressable-variable.good.al

@@ -0,0 +1,17 @@
+codeunit 50100 "Customer Lookup"
+{
+    procedure GetCustomerName(CustomerNo: Code[20]; var Name: Text[100])
+    var
+        Customer: Record Customer;
+    begin
+        if Customer.Get(CustomerNo) then
+            Name := Customer.Name;
+    end;
+
+    procedure Sample()
+    var
+        CustName: Text[100];
+    begin
+        GetCustomerName('10000', CustName);
+    end;
+}

microsoft/knowledge/style/var-parameters-require-an-addressable-variable.md

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+---
+bc-version: [all]
+domain: style
+keywords: [var-parameter, by-reference, pass-by-reference, literal, constant, compile-error, procedure-call]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# A `var` parameter must be called with a variable, never a literal or expression
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+When a procedure declares a parameter with `var`, that parameter is passed by reference: the callee writes back into the caller's own memory location. This means the argument at the call site must be an actual variable, something with an address. A string literal, a numeric constant, or a computed expression has no address to write back to, so passing one to a `var` parameter fails to compile. Before writing a call, check the callee's signature for `var` on each parameter position being supplied a literal or expression — if present, a variable declared in the caller's own scope must be used instead.
+
+## Best Practice
+
+Declare a variable in the caller's scope and pass it to the `var` parameter.
+
+See sample: [`var-parameters-require-an-addressable-variable.good.al`](var-parameters-require-an-addressable-variable.good.al).
+
+## Anti Pattern
+
+Passing a literal or a computed expression to a `var` parameter position fails to compile, because neither has an address the callee can write back to.
+
+See sample: [`var-parameters-require-an-addressable-variable.bad.al`](var-parameters-require-an-addressable-variable.bad.al).