TFL447 is a structured data format used by London Underground (LU) to exchange data between it's supply chain and LU's current asset management systems.
It is presented to the supply chain in a spreadsheet format that can be used as a source of information to generate additional dataset content for use during the design process.
The resulting design data could then be output as spreadsheet data for consumption by LU.
Similar results could also be achieved using ProjectWise Asset Tagging.
Either process will require significant work by appropriately experienced users and/or input from Bentley Professional Services.