From National Physical Laboratory website:
"Another convention sometimes used is that, since 12 noon is by definition neither ante meridiem (before noon) nor post meridiem (after noon), then 12 a.m. refers to midnight at the start of the specified day (00:00) and 12 p.m. to midnight at the end of that day (24:00). Given this ambiguity, the terms 12 a.m. and 12 p.m. should be avoided."
But, this is TeamStrange whose favorite answer to a question is, "It may be yes, but it could be no."
Ambiguity, what ambiguity?