# []: enabled, {}: enabled
a	input.mtextra	/^(def a)$/;"	d
b	input.mtextra	/^{def b}$/;"	d	extras:acceptCurlyBracket
c	input.mtextra	/^[def c]$/;"	d	extras:acceptSquareBracket
# []: disabled, {}: disabled
a	input.mtextra	/^(def a)$/;"	d
# []: enabled, {}: disabled
a	input.mtextra	/^(def a)$/;"	d
c	input.mtextra	/^[def c]$/;"	d	extras:acceptSquareBracket
# []: disabled, {}: enabled
a	input.mtextra	/^(def a)$/;"	d
b	input.mtextra	/^{def b}$/;"	d	extras:acceptCurlyBracket
