Optional parameters to scope this approval to (command, signingApplication, signingApplicationHash, hostname, osUsername, ipAddress, dataHash). Every value declared here must match at signing time or the sign call is denied; parameters left out are not restricted. A command must match exactly, apart from whitespace, so a different order of options is a different command. ipAddress is compared against the address the sign call arrives from and dataHash against the digest of the submitted payload, so those two hold even if a caller reports something else. A machine identity that declares a scope without naming ipAddress has it filled in with the address the request arrives from; send null to leave signing unrestricted by address.