I recently acquired a used Collings MT-O and wanted to confirm that the action was set to factory specs.
Here is the info provided by Collings:

String Height (measures top of fret to bottom of string):
Bass-side string height at 12th fret: 5/64"
Treble-side string height at 12th fret: 2/32"

Relief (measures distance from top of fret to bottom of string while fretting the 1st and 13th fret):
Relief at 5th Fret: .005"

Just thought I'd pass along the info.
Kelly