Thanks to all who replied to this and gave me info.
--- In firstname.lastname@example.org
> Can anyone help with the following? In the margin of a death cert
> to coal gas poisoning in 1939 is written what looks like the
> following: See Reg of Cor. Ents. Vol 6 page 64 31st May 1939.
> Is this a corrected entry or a corresponding entry and where can I
> see this? Any help appreciated the original entry is 2nd May for
> Holytown county of Lanark.