QXmlStreamReader::characterOffset sometimes returns incorrect values

Example:

QString test = "<speak>PLAIN <say-as></say-as></speak>";
QXmlStreamReader reader(test);
QVector<int> offsets = {0, 0, 7, 13, 21, 30, 38};
for (int i = 0; i < offsets.length(); i++) {
    if (offsets.at(i) != reader.characterOffset())
        qWarning() << "Wrong character offset. Is:"
                   << reader.characterOffset()
                   << "should be" << offsets.at(i);
    reader.readNext();
}

I think it is self explanatory.

1. If there is no explicit start document element like "<?xml version=\"1.0\"?>" then  reader positions itself on "<s". Probably is probing for start of element, not founding it and not reverting back buffer pointer.
2. Similar situation in case of characters token. It positions characterOffset on first "<" after text.

Am I right expecting that characterOffset should be positioned before "<" if one uses readNext etc?