After you have finished working on a file that has been checked out of Vault, or when you want to add a file to Vault for the first time, check the file into the Vault.
When you check in the file, you can optionally add comments with the file describing the changes made. The latest version of a file in the Vault is the last version that was checked in. Once a file is checked in, the latest changes become available for others to check out.
You can store any type of design data in a vault, including documents, spreadsheets, and model files. Non-Pro/ENGINEER files are added to the vault using Vault or related application-specific add-ins. To maintain the relationships among Pro/ENGINEER model files, you must use the Vault add-in for Pro/ENGINEER to add them to the vault.
The Add icon 
is displayed next to Pro/ENGINEER files that are not currently in the vault.