a Consensys factory class has this method:
//verifies if a contract that has been deployed is a Human Standard Token. //NOTE: This is a very expensive function, and should only be used in an eth_call. ~800k gas
function verifyHumanStandardToken(address _tokenContract) constant returns (bool) ...
Do certain constant methods use gas? Don't they just query the blockchain on the local node?
Can somebody clarifies this? Thanks.