Since Yosemite, Apple built-in the ability for Applications to automatically create a revision history of the worked performed. These files are located in the following location.

/.DocumentRevisions-V100

This folder is restricted from GUI access and requires the end user to use the terminal to gain access.

Example:  Pages

Pages stores it's info in the following path:

/.DocumentRevisions-V100/PerUID/501/1/com.apple.documentVersions/

Each file has a specific hash associated with it. Example: 852AAFEF-76F2-482A-AA0E-A3CD539826DA.pages

To view these "revisions" you will need to copy the files to the user's desktop and then view them in the correct application. With the above example we use the following command:

cp /.DocumentRevisions-V100/PerUID/501/1/com.apple.documentVersions/852AAFEF-76F2-482A-AA0E-A3CD539826DA.pages ~/Desktop/