How do I set AITag=1?

Hello all,

I'm trying to transfer history blocks from an older system to a newer system.
If I have my information right, I need to do the following:

To add a history block

1. Shutdown and disable AVEVA Historian.

2. While being sure to avoid time intersections, copy the old history blocks to the appropriate subdirectory for the current AVEVA Historian system.

3. For old tags created by Classic Storage, be sure to set AITag=1.

4. Enable and start Historian.

This information doesn't tell me where or how to set AITag=1. 

Can anybody please advise what I need to do here?

Thanks!