Single Line Font Export Settings?

I’m so , so close on this. I’m not getting single lines in my exported font files. Could anyone take a look at these settings and tell me if they are right?

(some may not be relevant and I may be leaving something crucial out):
Tools —> Options: check mark in “enable open contours”
Tools —> General: glyph outline fill mode " winding" and I’ve also tried “alternate”
Font ----> Properties —> General: Version is set to 5, and I’ve tried 3 and 4
Font —> Properties —> Characteristics: family kind is latin text; weight is set to book; all others say “any”
File —> Export Settings —>:
first tab: Output file is set to the folder I’m in, font name, and “save as type” is set to all;
outline format: true type
open type layout features: yes
legacy ‘kern’ table: yes
glyph names: regenerate for release
hinting: auto hinting
open contours: double stroke and I’ve tried single stroke. Double stroke results in a duplicate of the glyph right on top of itself with the end points joined. Single Stroke results in the one layer with a line from the first to the last like this:
show closure.jpg
Thanks so much in advance if anyone has pointers for me.

Windows doesn’t support single line fonts so it will close the contours by connecting the first point to the last point.

Single line fonts are supported on CNC engraving machines but you can’t use them on Windows.

Thanks for that info. I didn’t know that. Do they work on Macs?

I don’t know but I don’t think so, I don’t think it’s in the standard.

I think single line fonts with open contours are a specialist format only used by CNC engraving machines.