new week, more info.
So I followed up JVP's suggestion and compared file size - and lo and behold, the file size of the "strangely renamed" OT TTF was not identical to the file size of the actual font. I once more copied the font file to SYS:FONTS/_ttf/ (hope I got it right this time) - and now MORPHEUS can see both the OT TTF as well as the OT CFF.
Unfortunately, MORPHEUS is extremely buggy and has a lot of issues with actually loading the fonts. They are both in the fonts dropdown - but actually selecting them to start writing is a nightmare. BUT - I managed to select them in the end, and was able to WRITE with them. So this WORKS.
So to summarize: SYS:FONTS/_ttf/ seems to be a drawer that "some" applications tap into in order to get their fonts. And should the app be able to read OpenTypes, then these will be read. However, these fonts will NOT become part of the system fonts list.
However, the "official" way to install those fonts seems to be using a tool called FTManager. From what I understand, this tool analyzes the font file (which has to be a TTF?) and then creates two additional files (.font and .otag files). Unfortunately, I am not 100% sure if this is legal when using commercial fonts. I will need to check with our legal department. Most font foundries do not allow extracting font information from their fonts in order to create a new file.
The next question would be: does this actually work? OT TTF might look like TrueType fonts. But they are not. OpenType is a container format, and it includes a lot of possible options, like alternates or even contextual writing. I strongly assume this will either not work at all, or reduce the OpenType to its TrueType characters (and maybe not even all of them - OT TTF can hold up to 56 000 chars. But old TrueTypes usually only held 256 chars).
Will test this asap. Stay tuned. [ Edited by pikewerfer 26.07.2021 - 16:39 ]
Mac Mini 1.25 GHZ, 1 GB RAM, MorphOS 3.17