Doing a bit more research into "Source Han Sans":
https://github.com/adobe-fonts/source-han-sans
They offer it as:
- 1 single OTC font file
- Includes all languages and all weights.
- Note: Works in mac OSX 10.8 + Windows 10 (1703 or above).
- 7 OTCs
- Split per weight.
- Note: Works in mac OSX 10.8 + Windows 10 (1607 or above).
- 28 OTFs
- Split per language (Japanese + Korean + Simplified/Traditional Chinese) + per weight.
- Includes all the characters, just displays that language's variants where applicable.
- 28 Subset OTFs
- Split per language, then all the characters not in that language are removed.
You can read more about why in the readme, or this helpful explanation post:
Adobe's CJK Type Blog: "Source Han Sans: OTF, OTC, Super OTC, or Subset OTF?"
Turns out, OTC (or TTC) is an "OpenType/CFF Collection". (All technical details can be read in
Microsoft: "The OpenType Font File".)
Doubt this works in ebooks.
So, best bet would probably be to download the OTFs as needed, then embed. That would:
- Minimize ebook filesize
- Make sure the correct variant is drawn on the device.
- Not needing to rely on the device to support/understand language-switching fonts.
Complete Side Note: Over the years, "Arial Unicode MS" was another fallback font I sometimes used. Turns out, it's been deprecated.
See Microsoft's
The Old New Thing: "What happened to the Arial Unicode MS font?" and
Wikipedia: "Arial Unicode MS".