What the meaning of " (!0) " in ILNumerics Library?

Question

What the meaning of " (!0) " in ILNumerics just like this

return (!0)ILMathInternal.exp(this.m_mu);

and like this,

return 0.5 + (!0)ILMathInternal.log(this.m_sigma) + this.m_mu + (!0)ILMathInternal.log(ILMathInternal.sqrt(2.0 * ILMathInternal.pi));

Why we use this kind of expression---"(!0)" ?

Answer 1

(!0) has no meaning, it is not valid C#

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If I had to guess, which I do, I suspect the (!0) is how a decompiler has chosen to represent some IL code that has no C# representation.