Comment 394 for bug 1958019

Sorry, it was a typo of AC_VERB_SET_PROC_COEF.

In short, { 0x4XX, 0xYY } is equivalent with { AC_VERB_SET_PROC_COEF, 0xXXYY }
and { 0x5XX, 0xYY } is a combo of { AC_VERB_SET_COEF_INDEX, 0xXXYY }