Recommendation: use something like GIT (or one of the other fine source control systems out there) to checkpoint your work, and save the history of your org files.  It can even be set up in emacs to periodically save all org files and check in a snapshot. HTH, Brian ________________________________ From: Jude DaShiell To: emacs-orgmode@gnu.org Sent: Monday, July 18, 2011 4:36 PM Subject: [O] feature request A little data destruction protection.  I put together a table and had to destroy all copies of it after having tried to set up averages for a couple columns.  The averages didn't work and data got zeroed out and I lost an entire column of data that way.  One of my problems I'm sure was caused because I tried data gathering first then tried modifying the original table and adding the formulas later.  Next time I attempt anything with org and mathematics, I'll write my data set down in braille and ought to have done that with this data set as well.  What might have helped here a little is if a column is going to be put into existing columns the column inserts rather than overwrites any column that might be there.  The broken table I ended up with had six columns and two of those were single space columns out to the right with nothing in them.  There ought to have been before I did anything with formulas at most four columns in the table.  I did enter time stamps in as two separated date and time fields originally then when I read what all could be put into time stamps, I consolidated those first two columns into a single time stamp column.  I don''t know if that consolidation did further damage or not.