What Specific Guidelines Are Used for Maintaining an Organized Filing

What specific guidelines are used for maintaining an organized filing system?

A) Numeric filing with color-coding, because it is the simplest and most efficient system for most practices
B) Using approximately one file guide for every 50 to 100 folders
C) Leaving at least 12 inches on each shelf or in each drawer for working space within each file
D) Placing an outguide to mark a folder's place when it is removed from the file