Started my regex immersion /U

in the following does U stands for upercase, first letter?

[henry0]

I started (long time overdue) to take a deep immersion in regex but cannot figure out the answer to some questions:

For example
What that /U stands for?
preg_replace('/<a.*href="([^"])/U', '../$1', $url);
does it regard only the first uppercase character or all uppercases or something else?

I found a way to grasp the concept
1) Trying to understand the tutorialsSSS (so many!)
2) And when writing or reading a sample I read it but translate it in pure English if it does not make sense or does not seem to be logical then something got to be wrong.

[ergophobe]

Nope. It means "ungreedy".

Say you have:
text text text <a href="link">anchor</a>text text text <a href="link2">anchor2</a>

pattern: /a href="(.*)"/
returns: link">anchor</a>text text text <a href="link2

pattern: /a href="(.*)"/U
returns: link

The modifier "i" makes the search case-insensitive.

[us2.php.net...]

[henry0]

Understood; thanks.
A few more learning sessions
and I'll be dangerous!