If you right click on any column header (the tab with the column name) you get a pulldown with many cool options.
 
One of those options is "Properties",  wherein you can set some cool column properties.
 
 
and... one of those properties is checking the 'Use subfolders ' ... box.....
 
 
 
what that does is:  Instead of displaying the contents of any folder,  the contents of any Sub-folders of that folder are displayed instead.   (You add/modify/move around folders and sub-folders in the 'Folder Pane').
 
 
so... what is this good for ?
 
 
Two key uses.  (and actually this is a 'Masters' tip... so if you get this down..  you're at an 'advanced' level... Congratulations!).
 
 
 
1. A 'control panel'.
 
 
Let's say you have 4 key fields (folders):   Due Date,  Delegated to,  % Completed at last inspection, and Followup.   By putting all 4 as sub-folders to another folder, say 'Delagation', and having that folder be a column with subfolders enabled...  you'll see a little 'control panel' with each relevant item.. showing all in one box the key info and status for that item....   (it's pretty cool).
 
Tip:  keep the names of the sub-folders  MICRO SMALL...  ie.  super short.   Instead of due date.. use "Due" as the folder name,  instead of % Completed...  use just "%"... etc.   (You can make the column as wide as you need by right click on the column header and select column width, or by dragging the right side (bar) of the header column tab.)
 
 
 
2. A viewer.
 
 
Let's say you have 4 types of deadlines you deal with.  Deadlines that need 1 mos. notice, 1 weeks notice, 1 year notice, and 1 day notice.
 
You can set up a folder 'Deadlines'.  Under that folder,  set up 4 sub folders.  "M.", "W", "Y","D".  In the FOLDER properties (right click on folder in the folder pane to get there), assuming you set these up as date folders,  you can set an AUTOMATIC amount of notice or alarm for the items in each folder.  Each folder can have a different rule for notice and alarms.
 
How to use ?
 
In the outline you have one column for the deadline, "Deadlines".  You make it a sub-folder column.  To enter a deadline you click on the column and up pops a list with 4 places to enter a date (in our example).  You select the right placement.. ie.  M W Y or D, and enter the deadline date.  AUTOMATICALLy the proper deadline period is set.  When you press enter...  magically that deadline shows up in the column.
 
 
 
 
Note:  How to sort ?
 
With normal columns using a right-click then pressing U  will get a quick sort.   Sub-folder columns require an extra step, and an Advanced 'trick' to use quickly.   First the trick:  add all of the sub-folders you want to be able to sort to the end of your columns and minimize them (double click them, or shrink up their width).   You don't need to see them.. you just want them in the columns.    Then,  when you right click on any column and choose 'Sort', you can quickly select which column(s) you want to use as your sort keys.
 
 
 
 

Another example:
 
 
Gary B. asked, Quote:

 
    Here is one way to do that, using subfolders.
 
Set up a parent folder "Deadlines" with 2 sub-folders "A" (for alarmed) and "s" (for silent).  You can make Alarms AUTOMATIC in the Alarmed folder (but don't have to).   If not obvious,  both the "A" and "s" folders need to be DATE folders.  The Parent folder DOES NOT HAVE TO BE A DATE FOLDER... it can be a checkbox or anything else-- it doesn't matter-- it's really just a placeholder for the sub-folders.
 
 
Add the "Deadlines" to your notepad view, and set it as a 'subfolder' view column.  Now,  when you enter a deadline (and this works the same for appointments in place of deadlines, etc.),  you can choose to enter it in the "A" (alarmed) or "s" (silent)  field (folder).    The result:   All dates with an alarm are preceded by a "A" in your column,  all those without are proceeded by a "s".    Kind of cool.