Use the "OnRegistered" event:
The script works on the event for a new user registration. It checks that a new user has a default rights group "WEB Guests". If yes, the script renames him and adds the prefix "(Web client)" from the text constant.
Script text:
// ---------------------------------------
// Script created by Alexey Pikurov
// 01.06.2018 15:33:51
// ---------------------------------------
const
PREFIX = '(Web client)';
procedure OnRegistered(iCID, iUIN: integer; var iRole: integer; var bBlocked: boolean);
var
sGroupName, sNickName: string;
x: integer;
begin
sGroupName := mGetRoleNameByID(iRole);
if sGroupName = 'WEB guests' then begin
sNickName := mGetUserAttribute(iUIN, 'InternalNickName');
if pos(PREFIX, sNickName) = 0 then mSetUserAttribute(iUIN, 'InternalNickName', PREFIX + ' ' + sNickName);
end;
end;
begin
end.