Say you generate a child key using the path m/6'/4'/7'/99'/0/196, which 
is what your proposed path structure would be, and it results in the 
address 1DpY7PtPVURvjrGsdAjbZAZ7cL9GD8tc5w.

When the wallet notices a transaction in the blockchain that has 
1DpY7PtPVURvjrGsdAjbZAZ7cL9GD8tc5w as an output, it's going to have to 
lookup the address within its database to get the values 6/4/7/99/0/196, 
as there's no way to retrieve them from just the address.  So 
technically, you might as well just use m/account'/change/index if using 
hardened child keys, or m/change/index if not, as recommended, because 
the wallet will still function the exact same way.


On 06/20/2015 06:31 AM, Matt Smith wrote:
> I'm not sure I understand your question about the need to store paths in
> the wallet database -- there's no way to infer the path of an address
> inside an HD wallet from the address alone (short of an exhaustive
> search), and HD wallets need to store either the paths, addresses, or
> both that have been previously derived/used to monitor the blockchain
> usefully, but those facts aren't new or specific to this path format.
> The motivation for this path structure over standard bip44 is that it
> separates the concept of network (or which blockchain I'm using) and
> coin_type (or what kind of thing I'm sending over that blockchain).
> This is useful, for example, if I want to import a wallet into my
> application and I know that an account was in use at
> m/##'/0'/99'/0'
> where 99 is the identifier for, say, counterparty - I only need to check
> the addresses derived below that path for balances against
> counterpartyd. It may be worth pointing out that I expect multisig HD
> wallet imports to require master keys and a list of account paths – not
> a list of addresses, as it's very possible that a new address could be
> derived between the time when the wallet data was exported and when it
> will be imported.
> This use case might be very specific to our model, but the reason I
> figured we should request a BIP # for this is that to start using it, we
> need to pick a number for the purpose field and don't want to do it
> arbitrarily (and risk having to change it later) or overload 44 (which
> would be misleading).
> Did I either  a) answer  or  b) misunderstand  your questions?
> --
> Matt Smith | Gem
> | GH: @thedoctor
> On 6/19/15 2:25 PM, Matt @ Envrin Group wrote:
>> Hi Matt,
>> I think your best bet is probably just push it out privately via blog
>> post / Github, and see if it gains any traction with other developers.
>> I'm a little uncertain as to the relevance though.  All those variables
>> (purpose, network, asset_type, account, change, index) need to be stored
>> internally within the wallet database, as there's no way to retrieve the
>> path used from just the address, correct?  In that case, what's the
>> meaning of that exact path structure when a) it can't be retrieved from
>> just the address, and b) the values will be stored internally within the
>> wallet when you lookup the address.
>> Matt

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