Why is there an additional security tab in the properties windows for documents stored on an ntfs volume

This has been answered before, so I will cite the question to the answer here:

NTFS  stands for NT file system or sometimes New Technology File System). It is the file system that the Windows NT operating system uses for storing and retrieving files on a hard disk. For every file and/or folder permissions can be set that specify which groups and users have access to them, and what level of access is permitted. The security tab is for this purpose:to specify which user has which permissions (full control, modify, read&execute, read or write).NTFS file and folder permissions apply both to users working at the computer where the file is stored and to remote users accessing the file ( when the file is in a shared folder). 
 Read more on -