Meaning of (?s) in regex

I am very new to the regular expression arena. Recently I searched for a regular expression for Powershell that allows me to match a html tag <table> and I found the following in this site.

$content -match '(?s)<table[^>]+width\s*=\s*"300px"\s*.*?>(.*?)</table>'

I have been looking for all regular expressions references and books (Perl and Powershell) for the meaning of (?s) with no luck. It looks like a condition but missing the then part.

Can someone point me to the right direction for the meaning of this?

Thanks

"?" means 1 or 0 matches. "?s" enables dot matching newlines. A period is normally a wildcard that will match any character, save the newline.

According to [Regular Expressions reference site][1].

> Turn on "dot matches newline" for the remainder of the regular
> expression. (Older regex flavors may turn it on for the entire regex.)


[1]:

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