Sir Pete geeeeeeeeeee . . . . .
Looking at all of the information that he has put out / made available . . . . your depiction supplied above is not showing a Temp Display, but on the schematic that you showed, it is showing the connection point if using one.
This list of links below, is all that he is showing relevant to his other variants that he has shown, in which case he gets the Temp Displays from other sources, both as kits or DIY construction, which needs the u/p's hex programming code.
OR some units
are programmed and are thereby considering the use of a K type therrmocouple with them, such as those iron hand units use.
These videos are relating to his Hakko iron oriented soldering stations schemes . . .
https://www.youtube.com/channel/UC0dW_Q1nhPqbUQZvbeogOnQ/videos
https://www.youtube.com/watch?v=x7t2frBfW2c
The PCB layout pattern and component placements . . .
https://drive.google.com/file/d/0BwdhV7ro1izsc09qZzFmaUlrbEk/view
https://drive.google.com/file/d/0BwdhV7ro1izsaGtWY0s0S3RDNlU/view
And, also found in the content, a bit of a variant in PCB fabrication, in the respect of using a bit of the " weeping " effect of solvent into the toner, for its transferrance to the Copper PC blank..
Thus, effecting a chemical transfer, vice the typical thermal pressure of a hot clothing iron pressed into the paper backed PCB / toner pattern, onto the bare copper PCB blank.
Why not read abour it @ . . . . .
https://www.youtube.com/watch?v=W3lfMWt6nRk&feature=youtu.be
https://www.youtube.com/watch?v=lAFHgdVKB0c
I figure that in the one case of the blue poly sheet backing stuck to the "magazine" paper that the pattern was laser printed on was to
1 . . .add some more friction protection to that paper pattern, since it is to be pressure rubbed quite a bit.
2 . . .permit more retention time to the dampened paper, of its absorbed acetone+ ethanol / denatured alcohol mix, by slowing down air exposure time of evaporation.
You might just use adhesive backed Contact Paper, or a self stick laminating sheet, or side by side placed Scotch Clear Box packaging tape of the 2 inch width to the printed PCB pattern paper..
The final Q-tip clean up ? might actually be a degree of alcohol thinned out liquid rosin that is covering the board to then dry out into an antioxidant coating, for the bare copper pattern.
It is then being a flash flux coating for the forthcoming soldering of the PCB.
Thasssssssit . . . . .
73's de Edd . . . . .
I just hate it when my foot falls asleep during the day, because, you then just KNOW that it's going to be up all night.