Ignore this - but if you are looking to do column edits, use unix cut it's made for this job.
Assuming you have a regular tabulated text file, e.g. a directory listing.
Extract columns from 15 - 29 for the entire input. ls -l | sed 's/(^.{14})(.{14})(.*)/\2/' # ^---^ ^---------^ ^--------^ ^---^ ^