The docs from _utf8_on start with 
 _utf8_on(STRING)
         [INTERNAL] Turns on the UTF-8 flag in STRING.
         ....

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This implies that this function is not the recommended way. Or at leat, that it may change sometime. Another sign to avoid the usage is to me, that it starts with a underscore. This means 'private function' to me.
Boris

In reply to Re^2: Recommended way to set the utf8 flag without altering the data by borisz
in thread Recommended way to set the utf8 flag without altering the data by borisz

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