(PHP 7)
IntlChar::isUUppercase — Check if code point has the Uppercase Unicode property
public static IntlChar::isUUppercase ( mixed $codepoint ) : bool
Check if a code point has the Uppercase Unicode property.
 This is the same as IntlChar::hasBinaryProperty($codepoint, IntlChar::PROPERTY_UPPERCASE) 
Note:
This is different than IntlChar::isupper() and will return
truefor more characters.
codepoint
The int codepoint value (e.g. 0x2603 for U+2603 SNOWMAN), or the character encoded as a UTF-8 string (e.g. "\u{2603}")
 Returns true if codepoint has the Uppercase Unicode property, false if not. 
Example #1 Testing different code points
<?php
var_dump(IntlChar::isUUppercase("A"));
var_dump(IntlChar::isUUppercase("a"));
var_dump(IntlChar::isUUppercase("Φ"));
var_dump(IntlChar::isUUppercase("φ"));
var_dump(IntlChar::isUUppercase("1"));
?> The above example will output:
bool(true) bool(false) bool(true) bool(false) bool(false)
IntlChar::PROPERTY_UPPERCASE
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    https://www.php.net/manual/en/intlchar.isuuppercase.php