Hi Gavin,
I believe this is controlled by the “Assembly Code” type parameter in Revit, which is based on Uniformat classification. In order to change this you would have to edit the type settings for your finish floor assembly. I know that some firms have specific BIM standards when it comes to editing these classifications so I would double check that there is no conflict first. From my understanding, Tally only reads the first letter and two numbers in the assembly code, although some BIM standards require up to 4-digit classifications depending on the project/client. It’s likely that Revit has certain classifications preloaded for floor assemblies.
Hope this helps.
- Brie