Before the Omni Group created OmniOutliner, there was Symantec MORE 3.1 (Mac) and GrandView 2.0 (DOS) . I was a heavy user of MORE, but I also owned GrandView. Like OmniOutliner, GrandView combined features of a traditional outliner with a spreadsheet (columnar metadata).
Recently Jim W and Daniel G scanned the GrandView Reference Manual. It's a bit of history, both of an innovative software app and of a time when floppy disks shipped with lovingly prepared paper manuals. Grab it while it's hot!
(I'll eventually move the files to my personal site and fix up the above link, but it should work for the moment.)
 OmniOutliner 3 imported MORE 3.1 outlines. I don't know if that's true of version 4, I haven't upgraded. I wouldn't blame them for dropping that feature!
Update 4/21/2014: I’ve yet to update my old web page, and I’ve more files from Jim and Daniel to post, but life is hectic. In the meantime I’ll share here a note from Gregory J on running GV in a DOS emulator on Win64:
Just wanted to follow up with you to let you know that I found a pretty easy way to run Grandview inside 64-bit Windows 8.1. I downloaded the "DOSBox-0.74" DOS Emulator Program and install it (the 32-bit works fine under my 64-bit Win8)
Next, I put my Grandview Program Files and Data Files into a subdirectory c:\GV
I navigated to C:\Program Files (x86)\DOSBox-0.74 and I Run "DOSBox.exe"
At the Z prompt type MOUNT C C:\GV
At this point I'm able to run Grandview perfectly. More importantly I'm able to EXPORT my Outline contents into an ASCII File (a/k/a a Text File) into the c:\GV subdirectory. Then I'm able to cut N' Paste text in this text file to use elsewhere inside of Windows 8. My goal is to find OLD data I have stuck inside Grandview and get it copied so I can use that Data in new programs under Win8.
BTW, Pressing alt-enter will switch to Full Screen (making GV highly usable) and inside GV pressing Ctrl-2 will expand everything in the outline to make for a GREAT text file export.
The DOSBox Tutorial is at http://www.dosbox.com/wiki/Basic_Setup_and_Installation_of_DosBox