syn region factorDefnDelims start=/\v<M:>/ skip=/\v<!>.*/ end=/\v<\S+%(\_\s+%(!>.*)?)+\S+>/ contains=@factorComment skipempty keepend contained
syn region factorDefnDelims start=/\v<M::>/ skip=/\v<!>.*/ end=/\v<\S+%(\_\s+%(!>.*)?)+\S+>/ contains=@factorComment nextgroup=factorEffectSkip skipempty keepend contained
syn region factorDefnDelims start=/\v<CONSTRUCTOR:>/ skip=/\v<!>.*/ end=/\v<\S+%(\_\s+%(!>.*)?)+\S+>/ contains=@factorComment nextgroup=factorEffectSkip skipempty keepend contained
syn region factorDefnDelims start=/\v<M:>/ skip=/\v<!>.*/ end=/\v<\S+%(\_\s+%(!>.*)?)+\S+>/ contains=@factorComment skipempty keepend contained
syn region factorDefnDelims start=/\v<M::>/ skip=/\v<!>.*/ end=/\v<\S+%(\_\s+%(!>.*)?)+\S+>/ contains=@factorComment nextgroup=factorEffectSkip skipempty keepend contained
syn region factorDefnDelims start=/\v<CONSTRUCTOR:>/ skip=/\v<!>.*/ end=/\v<\S+%(\_\s+%(!>.*)?)+\S+>/ contains=@factorComment nextgroup=factorEffectSkip skipempty keepend contained