[luatex] Question about tex.setmath(..., ..., ...) [hope this is the right list]

[Akira Kakuto]

Dear Graham,

\directlua{
tex.setmath("global", "fractionnumup", "display", 131072)
tex.setmath("global", "fractionnumvgap", "display", 163840)
}

\[ formula
\]

didn't work. But

\[
\directlua{
tex.setmath("global", "fractionnumup", "display", 131072)
tex.setmath("global", "fractionnumvgap", "display", 163840)
}
formula
\]

did work.  So is "global" not working?

Best,
Akira