Places CSV Import/Export field to store local server id

I need to synchronise the data between the wp server and the server that supplied the original data (Rails server).

So the Rails server exports data to a csv file. This is then uploaded to the wp server via the csv import tool.

I then export the places to csv so I can import the data back into the rails serve and set the unique id from the wp server on the rails server records. This enables me to then hook directly (remotely) into the wp server from the rails server and update various meta keys that are otherwise not exposed through the api or through the csv import tool

In order to accurately match the records exported from wordpress I need a field in both the import and the export csv files that I can use to set the unique ID from the Rails server.

Is there an appropriate field I can use for this?