Larry,
Each manufacturer uses a unique structure and different set of midi and / or sysex commands for their styles. It's basically along the same lines as trying to use a raw ( unconverted ) Korg .sty file in a Tyros. It simply won't work.
.sty just happens to be the extension that many of the manufacturers choose to use in order to give their styles an extension that is compatible with use on a computer. A korg .sty file is in no way similar to a yamaha .sty file. In fact, one Korg .sty file holds 16 individual styles inside of it. One Yamaha .sty file holds one style.
A korg style consists of individual and seperate midifiles for each variation in a style. Each midifile has a unique name ( such as v1cv1 ) that a PA80 scans and finds when you call up a particular variation.
Yamaha styles are simply a single midifile that contains the midi data of all of the variations in a style, along with markers that the arranger scans and detects when you call up a certain variation. The Yamaha .sty file also uses sysex commands that define other style parameters.
BIAB styles work in a different way than either. Each style variation has several sub-variations within, with numerical values assigned to each of the "sub-variations" that help determine how often and / or where in a song a particular sub variation will play.
The extensions .fxb and .fxp other examples of this. These are the propietary extension that Steinberg created for single patch ( fxp) and multiple patch or effect banks ( fxb ) that are used in mostly all Vst plug ins and instruments. Each plug in manufacturer sets his / her banks and patches up to match the software, but these are never interchangeable. In other words, I can't use an .fxb bank made for Arturia's CSv80 inside of NI's Pro 53. In fact I can't even use some of the .fxb banks from Pro 52 inside of Pro 53.
Hope this helps..
Cheers,
AJ
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AJ