What does preg_match isU mean?

What does preg_match isU mean by the isU (. *) after the regular expression (. *) [this article is from the Internet (www.68idc.cn)]? What does the isU parameter mean? This is the modifier in the regular expression. I is used to search for uppercase and lowercase letters at the same time, and s is a dot (.) match All characters, including line breaks. if s is not set, linefeed is not included. U reverses the matching quantity.

Preg_match isU represents what is the meaning of the regular expression after/(. *)/isU [this article from the Internet (http://www.68idc.cn)], isU parameter represents what meaning? This is the modifier in the regular expression. I is used to search for uppercase and lowercase letters at the same time, and s is a dot (.) match All characters, including line breaks. if s is not set, linefeed is not included. U reverses the matching quantity.

Meaning of preg_match isU

Regular followed by/(. *)/isU [this article from the Internet (http://www.68idc.cn)], "isU" parameter represents what do you mean?
This is the modifier in the regular expression.
I is used to search for uppercase and lowercase letters at the same time,
S indicates that the dot (.) matches all characters, including line breaks. If s is not set, the line breaks are not included.
U reverses the value of the matching quantity so that it is not the default repetition, but becomes behind "?" To be repeated.