See www.zabbix.com for the official Zabbix site.
Generic API behavior
Input and output
- Parameters that are set to NULL must be treated the same way as if they are missing: we either substitute them with default values or trigger an error. Null values for update methods must be ignored.
- The API must not return NULL values; they must be replaced with an equivalent empty values (zero, empty string or empty array).
- Within one request repeated updating of the same record isn't supported.