[DOC][l3regex] The concept "the case of the character properties" is confusing.

[SainoNamkho]

The option (?i) makes the match case insensitive (identifying A–Z with a–z; no
Unicode support yet). This applies until the end of the group in which it appears,
and can be reverted using (?-i). For instance, in (?i)(a(?-i)b|c)d, the letters a
and d are affected by the i option. Characters within ranges and classes are affected
individually: (?i)[Y-\\] is equivalent to [YZ\[\\yz], and (?i)[^aeiou] matches any
character which is not a vowel. Neither character properties, nor \c{...} nor \u{...}
are affected by the i option.

The concept "character property" is not introduced in the documentation part. In the implementation part,
45.2.4 Character property tests, it says

These character properties are not affected by the (?i) option

Then what's the case of the character properties? There aren't opposite case counterparts of these character classes.
For example, the uppercase-form a string matching \w+\d still matches \w+\d.

I infer from the implementation that the upper-case form of \d means \D, but it is strange to say the case of escaped characters in regex. And this is not consistent, the upper-case form of \c{a} is \c{A}, not \C{A} or \C{a}.