The 3-transposition groups that act on vertex operator algebras in the way described by Miyamoto in [Mi] are classified under the assumption that the group is centerfree and the VOA carries a positive-definite invariant Hermitian form.
@article{1158241926,
author = {MATSUO, Atsushi},
title = {3-transposition groups of symplectic type and vertex operator algebras},
journal = {J. Math. Soc. Japan},
volume = {57},
number = {4},
year = {2005},
pages = { 639-649},
language = {en},
url = {http://dml.mathdoc.fr/item/1158241926}
}
MATSUO, Atsushi. 3-transposition groups of symplectic type and vertex operator algebras. J. Math. Soc. Japan, Tome 57 (2005) no. 4, pp. 639-649. http://gdmltest.u-ga.fr/item/1158241926/