not all item types and fields available in item mass update

First, not all item types are available for mass update - "IPMI agent", "SSH agent", "TELNET agent", "Calculated" are missing. "Zabbix aggregate" is repeated two times. The contents and the ordering in the dropdown should be consistent with the item list in item creation form.

Second, not all fields are available for mass update. For instance, "Authentication method", "User name", "Public key file", "Private key file", "Password", "Executed script", "IPMI sensor", "Formula" are missing. Maybe others are missing, too. Before fixing that, it should be discussed whether all of them are actually needed.