which standard is used for REGEX regular expression functions in TD14.10

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which standard is used for REGEX regular expression functions in TD14.10

I'm want to confirm what regex standard is used for TERADATA's 14.10 database engine,

There's POSIX, basic, extended, emacs/perl/python varieties but I couldn't find a good reference two exactly what is used. I see that matches don't require escaping parenthesis making me think it's extended regex, but I've seen [:word:] POSIX style also...