Nice variety there! Always a cool one to find as most dates do not have the digit within the dentil's
Just a quick not to those of you who do not already know why they have been placed there, The die makers would test the hardness of the die that would be used in the minting process.
They tested the annealing process by using the digit marking tool and tapping upon the edge of the coin to see that its hardness was correct....My personal SWAG or opinion is that if it was correct that the coin was ready to be put into production,, if not it was to be reworked until in proper condition.. sometimes the imprint from the testing was not corrected or felt that it would show up as a blemish within the dentil's....The first years of mint production was plagued with many problem,,,Its a very interesting Read if any ones interested, its in the
VAM Encyclopedia book and used to be on the PCGS website in there book section that could be read online not sure if it can be done today I haven't been there in a long time...
Good stuff, perhaps someone can give us an update on the current status or availabillity to find and read it online...G