Revit IDs

[michael_pescht]

Hi everyone,

first of all: i'm new here, so i apologize in advance for any formal errors

there are several explainations for the used IDs in Revit.

Unfortunately, I have not found a complete definition of all IDs in a document / post. Therefore I would like to have my compilation checked here in the forum. Thanks in advance:

Revit Element UniqueId
"UniqueId"
Is a stable unique identifier for an element within the document. Each element has such a unique identifier, which is returned by the API as a string.
Beispiel: 626f5187-9a17-4713-98b7-532ca3cc31b1-000dabe8
Hexadecimal sequence: 8-4-4-4-12-8 (GUID + 😎
Revit: UniqueId = EpisodeId (8-4-4-4-12) + Hexadecimal(Id) (8)

Revit EpisodeId
"EpisodeId"
Is the first part of UniqueId, including the characters of the sequence 8-4-4-4-12 and refers to the project and the session.
Beispiel: 626f5187-9a17-4713-98b7-532ca3cc31b1

Revit element Id
"Id"
Example decimal: 895976
Example hexadecimal: 000dabe8
Is the unique identification for an element within a single project.

Revit DWF GUID (Export GUID)
"DwfGuid"
Hexadecimal version of the ifcGUID
Hex(IfcGUID) = DWF GUID
Beispiel: 626f5187-9a17-4713-98b7-532ca3c19a59

Revit ifcGUID
It is a 22 character code (string) using the 64 character base which includes numbers, upper and lower case letters and some special characters. Although it looks completely different from other GUIDs, the IFC GUID is completely identical to the DWF GUID, but is expressed with a different encoding to make it shorter and easier to understand.
Compressed version of the DWF GUID.
Hex(IfcGUID) = DWF GUID
Beispiel: compress(626f5187-9a17-4713-98b7-532ca3c19a59)

Revit ExternalId
The external ID of a geometry object.
Beispiel: 626f5187-9a17-4713-98b7-532ca3c19a59-000dabe8
Revit: ExternalId = DwfGUID + "-" + Hex(ElementId)

[jeremy_tammik]

Dear Michael, 

Thank you for your very valuable compilation. I searched for the information I am aware of on element ids and unique ids and compiled the following two lists for you:

Element Id

• Retrieving Newly Created Elements in Revit 2011
• Comparing Element Id for Equality
• DWG Issues and Various Other Updates
• Element Id – Export, Unique, Navisworks and Other Ids
• CreateLinkReference Sample Code
• Family Category, Element Ids, Transaction Undo and Updates
• DevDay Conference in Munich and WPF DoEvents
• Revit versus Forge, Ids and Add-In Installation
• Retrieving Newly Created Element Ids
• RevitLookup Search by Element and Unique Id
• Element Identifiers in RVT, IFC, NW and Forge
• Immutable UniqueId and Revit Database Explorer
• 64-Bit Element Ids, Maybe?
• Configuring RvtSamples 2024 and Big Numbers
• 64 Bit Ids, Revit and RevitLookup Updates

Unique Id

• UniqueId, DWF and IFC GUID
• Melbourne Day Two
• Real-World Concrete Corner Coordinates
• IFC GUID Generation and Uniqueness
• Copy and Paste API Applications and Modeless Assertion
• Element Id – Export, Unique, Navisworks and Other Ids
• Unique Names and the NamingUtils Class
• Understanding the Use of the UniqueId
• Back from Easter Holidays and Various Revit API Issues
• Consistency of IFC GUID and UniqueId
• Revit versus Forge, Ids and Add-In Installation
• RevitLookup Search by Element and Unique Id
• Unique Id and IFC GUID Parameter
• Immutable UniqueId and Revit Database Explorer

I have not checked exhaustively, but afaict all the info correlates with your summary.

Cheers

Jeremy