ON. [eu], [iu] became [ū]; [{eu|iu}] > [ū]

ON. [eu], [iu] became [ū]; [{eu|iu}] > [ū]
GS/§4.28 GS/§4.29 GS/§4.60 WGCH/§76i [PIE eu > Brit ou > W u] §76xi [PIE iu, ēu > Kelt iu > W iw or yw] @@@,

Exceptions:

Order (02600)

After 00900 first in pair of voiced stops vocalized ᴹ✶libda > N. glúð Ety/LIB²

Phonetic Rule Elements

[eu] > [ū] ✧ PE19/25 (eu > ou > ū)
[iu] > [ū] ✧ PE19/25 (iu > ū (ī))
[ˌeu] > [io]

Phonetic Rule Examples

beuja- > būja- eu > ū ᴹ✶beuyā́- > ON. buióbe ✧ Ety/BEW
ndeuro > ndūro eu > ū ᴹ✶ndeuro > N. Dûr ✧ EtyAC/NDEW
pʰeuja- > pʰūja- eu > ū ᴹ√PHEW > ON. phuióbe ✧ Ety/PHEW
gliuda > glūda iu > ū ᴹ✶libda > N. glúð ✧ Ety/LIB²
jiuta > jūta iu > ū ᴹ√ÑIW > ON. (g)yūta ✧ EtyAC/ÑIW
piuja- > pūja- iu > ū ᴹ√PIW > ON. puióbe ✧ Ety/PIW
sjiule > sjūle iu > ū ᴹ√SIW > ON. hyūle ✧ Ety/SIW
tiuja- > tūja- iu > ū ᴹ√TIW > ON. tuio- ✧ Ety/TIW
tiuka > tūka iu > ū ᴹ✶tiu̯kā > ON. tūka ✧ Ety/TIW
beuro > bioro ˌeu > io ᴹ✶beu̯rō > biuro > ON. bioro ✧ Ety/BEW
sneuma > snioma ˌeu > io ON. sniuma/snȳma > N. hniof/hnuif ✧ Ety/SNEW
sneuma > snioma ˌeu > io ᴹ√SNEW > ON. sniuma/snȳma ✧ Ety/SNEW

ᴱN. [eu], [iu] became [io]; [{eu|iu}] > [io]

See OS. [eu] became [iu] for discussion.

Phonetic Rule Elements

[eu] > [io] ✧ PE15/64 (eu̯ > io); PE15/64 (eu̯ > ı̯au̯ > io)
[iu] > [io] ✧ PE15/64 (iu̯ > io)

G. [eu], [iu] became [io] or [iu]; [{eu|iu}] > [io|iu]

See OS. [eu] became [iu] for discussion.

Phonetic Rule Elements

[eu] > [io]
[iu] > [io]
[eu] > [iu] ✧ PE15/13 (eu > iu; unacc. io/yo)

Phonetic Rule Examples

nreu > nrio eu > io ᴱ✶n’reu̯ > G. †drio ✧ GL/30
giul > giol iu > io ᴱ√giu̯i > G. giol ✧ GL/39
giuθ > gioθ iu > io ᴱ√giu̯i > G. gioth ✧ GL/39
giuθra- > gioθra- iu > io ᴱ√giu̯i > G. giothra- ✧ GL/39
gʷiuθ > gʷioθ iu > io ᴱ√gu̯iu̯ > G. gwioth ✧ GL/42