REGISTER.ID Function in Excel: ID of a Registered DLL Function

REGISTER.ID Function in Excel: ID of a Registered DLL Function 1
⏱ 1 min readUpdated 5 October 2026

Add-in & automationLevel: ExpertAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. REGISTER.ID in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions

REGISTER.ID returns the register ID of a DLL function for CALL. Same legacy, same security restrictions.

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Syntax

=REGISTER.ID(module_text, procedure, [type_text])
Argument What it means
arguments Depend on the DLL or RTD server

Examples

Example 1

=REGISTER.ID(module_text, procedure, [type_text])

Result: (depends on the installed server). See the worked example table below for more cases.

REGISTER.ID in practice

Where you will use it

  • Understanding very old workbooks
  • Developer integrations
  • Auditing legacy files

Worked example

ExampleFormulaResult
see syntax=REGISTER.ID(module_text, procedure, [type_text])(depends on the installed server)

Needs external software, so it is not calculated here.

Mistakes people make

MistakeWhat to do instead
Expecting it to work out of the boxNeeds the external server/DLL and trust settings
SecurityOnly use RTD servers and DLLs from trusted vendors

WEBSERVICE

📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.

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