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-Comments for the Partially Signed Transaction Format
\ No newline at end of file
+# Comments for the Partially Signed Transaction Format
+
+* Partial signature entries use the map key `{0x02}|{public key}`.  However, a single public key may be involved in signing multiple inputs, and the signature will differ in each one.  Since the map keys are to be unique, this is a problem.  I suggest the following map key instead: `{0x02}|{input index}|{pubkey index}`
+
+* HD derivation entries waste space by repeating the public key.  I recommend using the following map key instead: `{0x03}|{input index}|{pubkey index}`, which also matches previous point.