Acetamide, N-[(1S,2S)-2-[(3R,5S,6R)-6-[3-fluoro-2-(fluoromethyl)-2-methylpropoxy] -5-methyl-3-morpholinyl]-1-[(3-fluoro-5-hydroxyphenyl)methyl]-2-hydroxy ethyl]-, mono(trifluoroacetate) (salt)