2. The method according to claim 1 , where the user-encoded target length of the target string comprises a user-maintained selection time of a symbol of the sub-sequence, and where detecting, via a user input device as part of user entry of a sub-sequence of a sequence of symbols of a target string, a user-encoded target length of the target string comprises: detecting, during user entry of the symbol of the sub-sequence, a user-maintained press of an input key that enters the symbol of the sub-sequence for a defined duration of time that corresponds to a defined target length; and setting the target length as the defined target length that corresponds to the defined duration of time for which the user-maintained press of the input key that enters the symbol of the sub-sequence was detected.
4. The method according to claim 2 , where setting the target length as the defined target length that corresponds to the defined duration of time for which the user-maintained press of the input key that enters the symbol of the sub-sequence was detected comprises: setting the target length to a corresponding target length defined to correspond to a measured selection time of a last symbol of the sub-sequence; and where enabling user selection of one of the eligible strings via the user input device as the target string comprises: displaying the eligible strings; prompting the user to select one of the eligible strings; detecting a selection of an eligible string; and completing the sub-sequence automatically in response to detecting the selection of the eligible string.