I needed a lot of help with this - largely because my initial Google search led me to two wrong names to go with one of my forenames - but am very glad I persevered.
Opt0 - it sounds to me like you're on the right lines. I'm not sure why your fourth letter would be a problem. For me, one transformation changed it to the only other possible letter; the second changed it back again.
Crowdedmorning- there's a reason why there is an 'appropriate location' for the next member of the set, which I take as a pointer for where the entry number should go.