Update eip-9999.md

EIPS/eip-9999.md

@@ -34,6 +34,11 @@ The `LOG` of a value-transferring transaction should be placed before any logs c
 
 This is the simplest possible implementation that ensures that all ETH transfers are implemented in some kind of record that can be easily accessed through making RPC calls into a node, or through asking for a Merkle branch that is hashed into the block root. The log type is compatible with the ERC-20 token standard, but does not introduce any overly-specific ERC-20 features (eg. ABI encodings) into the specification.
 
+### Open questions
+
+1. Should withdrawals also trigger a log? If so, what should the sender address be specified as?
+2. Should fee payments trigger a log? It would ensure "completeness", in the sense that you can compute the exact current balance table by watching logs, but it would greatly increase the number of logs, perhaps to an unacceptably high amount.
+
 ## Backwards Compatibility
 
 No backward compatibility issues found.