[Lazarus] UTF8String and UTF8Delete

[Jürgen Hestermann]

Am 2015-12-10 um 18:22 schrieb Juha Manninen:
> On Thu, Dec 10, 2015 at 6:49 PM, Jürgen Hestermann
> <juergen.hestermann at gmx.de> wrote:
>> How can I use UTF8Delete on an UTF8string?
> You can't. Please read this :
>   http://wiki.freepascal.org/Better_Unicode_Support_in_Lazarus
> "String" type is UTF-8 and it works now (almost) transparently without
> explicit conversions.
>
Where do you read this?
I only found:

"Since FPC 2.7.1 the default system codepage of the RTL can be changed to UTF-8 (CP_UTF8). So Windows users can now use UTF-8 strings in the RTL. "

It *can* be changed (but how?).

And what happens to the UTF8String type?
It can never be used anymore?
Why does it exist?