It is the Boot Controller/Manager configuration directory.
See below how to get into it if you have a multi-boot system.
But first, you will want to have a Repair
boot disk on hand so you can get into the Recovery Console.
You can create one in the Backup and Restore
utility. It gives you all the tools you need to fix the master boot record and other startup problems.
Here is an article about that:
How to Create a System Image Backup in Windows 7, 8, or 10
This article shows both how to make a full system image backup, but more importantly it shows how to make the repair disk.
Once you have the repair disk you will be ready.
If needed, boot that disk to get to this screen:
Then follow the instructions in this article:
HOW TO USE A SYSTEM REPAIR DISC TO RESTORE WINDOWS 7
BCD is especially interesting when you have a multi-boot system.
You can get into it using the windows bcdedit
command, or download the third-party GUI front end for it here:
Visual BCD - Boot Repair Tool
You found it. See my answer below: – SDsolar – 2017-09-19T01:55:25.977