"A negative assert matches anything but its contents. It does not consume any characters in the target sequence. For example, "(!aa)(a*)" matches the target sequence "a" and associates capture group 1 with the subsequence "a". It does not match the target sequence "aa" or the target sequence "aaa"."
What actually works on Opus is:
Is it an error of Microsoft's documentation or perhaps the regex flavor changed and Opus' documentation is now linking to the wrong page?
I have a help file (chm) titled Windows Scripting Technologies. It covers JScript and VBS Script. The page for regular expression syntax seems correct.
I don't know from where I got it, but it seems Microsoft makes it available for download. Could it be distributed with Opus and linked to from Opus own documentation? Maybe it is a better option than linking to online pages?
I doubt it is as simple as asking with a company that size. It may involve legal sign-off which would make it not even worth their time to respond.
If we're talking about contacting Microsoft then reporting the documentation error seems a more likely path to success, and would fix it for everyone. I don't know how good they are at fixing such things these days, though.
The feedback ("is this page helpful?") link at the bottom of the documentation page suggests they may listen. I'll report it later on, but another report can't hurt if you want to as well.