Merge pull request #57 from Curabis/rule/document-reports-should-default-to-word-layout

[BCQuality] Document reports should default to Word layout, not RDLC

custom/knowledge/performance/document-reports-should-default-to-word-layout.md

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+---
+bc-version: [all]
+domain: performance
+keywords: [report-layout, word-layout, rdlc, document-report, sandbox-app-domain, rendering]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Document reports should default to a Word layout, not RDLC
+
+## Description
+
+When a new or extended report is a document report — an invoice,
+statement, order confirmation, or any report meant to be printed, emailed,
+or exported as a single-record document — its default rendering layout
+should be `Word`, not `RDLC`. This is Microsoft's own current
+recommendation, not just a style preference: RDLC layouts run in a
+sandboxed app domain that only lives for the current report invocation,
+which is slower for UI-related actions (like sending the resulting
+document by email) than a Word layout, which is not subject to that
+sandbox constraint.
+
+This does not apply uniformly to every report. Tabular/list reports with
+heavy aggregation or complex calculated columns are still often a better
+fit for RDLC (or Excel), because Word's table-based layout model doesn't
+handle that as well. The distinguishing question is whether the report
+represents one structured document per record (Word) or a data listing
+(RDLC/Excel) — not "RDLC vs. Word" as a blanket choice.
+
+## Best Practice
+
+```al
+report 50100 "Sales Quote Confirmation"
+{
+    // ...
+    rendering
+    {
+        layout(Word)
+        {
+            Type = Word;
+            LayoutFile = './Layouts/SalesQuoteConfirmation.docx';
+            Caption = 'Word Layout';
+        }
+    }
+
+    DefaultRenderingLayout = Word;
+}
+```
+
+## Anti Pattern
+
+```al
+report 50100 "Sales Quote Confirmation"
+{
+    // ...
+    rendering
+    {
+        layout(RDLC)
+        {
+            Type = RDLC;
+            LayoutFile = './Layouts/SalesQuoteConfirmation.rdl';
+        }
+    }
+
+    DefaultRenderingLayout = RDLC;
+}
+```
+
+Building a document report's default layout in RDLC by default — because
+it's the more familiar tool, or because a template happened to use it —
+inherits RDLC's sandboxed-app-domain performance cost for no reason tied
+to the report's actual content or calculation needs.
+
+## Source
+
+Microsoft Learn, "Creating an RDL layout report" and "(Obsolete) Set the
+Layout Used by a Report": "RDL layouts can result in slower performance
+with document reports... we recommend that you design Word layouts
+instead of RDL... reports are not impacted by the security constraints on
+sandbox app domains like they are with RDL layouts" — and "Document
+reports (not lists) that use a Word report layout are typically faster
+than those that use an RDLC report layout." Verified 2026-08-12.