VediramOffice Add-in Types
The different ways Office apps can be extended, which app supports which, and the types Deck manages
Microsoft Office can be extended in several different ways, and not every Office application supports every method. This page explains the landscape and shows which combinations Deck manages today.
The extensibility mechanisms
- COM add-in - the universal Windows add-in model. Registered under
...\Office\16.0\<App>\Addins\<ProgID>and switched on or off with aLoadBehaviorvalue. Every classic Office desktop app supports it. - VSTO add-in - a managed (.NET) add-in built on top of the COM model. It uses the same
LoadBehaviorswitch, so from a management point of view it behaves like a COM add-in. - XLL - a native Excel-only add-in that plugs directly into Excel's calculation engine.
Loaded from Excel's numbered
OPENlist rather thanLoadBehavior. - Automation add-in - COM components exposing Excel worksheet functions, also loaded
from Excel's
OPENlist. Excel-only. - RTD server - a real-time data server invoked by the Excel
=RTD()worksheet function. Excel-only. - VBA - macros embedded inside a document or template, governed globally by the Trust Center rather than per add-in.
- Web add-in - the modern cross-platform model (Office.js + a manifest), delivered through a trusted catalog or the marketplace.
Which app supports which
| App | XLL | Automation add-in / RTD | VBA | COM add-in | VSTO | Web add-in |
|---|---|---|---|---|---|---|
| Excel | ✓ (only host) | ✓ | ✓ | ✓ | ✓ | ✓ |
| Word | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ |
| PowerPoint | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ |
| Outlook (classic) | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ |
| Outlook (new) | ✗ | ✗ | ✗ | ✗ (dropped) | ✗ (dropped) | ✓ (only model) |
| OneNote | ✗ | ✗ | ✗ (no VBA) | ✓ | ✗ | ✓ |
| Visio | ✗ | ✗ | ✓ | ✓ | ✓ | diagrams only |
| Project | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ |
| Access | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ |
| Publisher | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ |
✓ supported · ✗ not supported / not applicable
A few things worth knowing:
- XLL, Automation add-ins, and RTD are Excel-only - they exist to feed Excel's recalculation engine, which no other Office app has.
- COM add-ins are the common denominator - every classic desktop app supports them, including OneNote, Visio, Project, Access, and Publisher.
- The new Outlook for Windows drops COM and VSTO entirely and supports only web add-ins. Classic Outlook still supports all of them.
- OneNote has no VBA, and Access and Publisher have no VSTO or web add-ins.
What Deck manages
Deck focuses on the add-in types that have a per-add-in on/off switch it can control:
| Type | Deck support |
|---|---|
| COM & VSTO add-ins | Discovered and switched via profiles across Excel, Outlook, Word, and PowerPoint - see Add-in Management. |
| Excel XLL add-ins | Managed through the OPEN list, including IT-controlled load order and force on/off - see Managing Excel XLL Extensions. |
| Web add-ins | Discovered, and side-loaded for your organization from an IT-supplied trusted catalog. |
Types Deck does not manage today: Automation add-ins and RTD servers (Excel), VBA macros (governed by the Office Trust Center, not a per-add-in switch), and COM add-ins in apps other than Excel/Outlook/Word/PowerPoint. For where each managed type lives in the registry, see Registry Details.