We have aggregated checks documented:

https://www.zabbix.com/documentation/current/manual/config/items/itemtypes/aggregate

But it lacks at least 2 things:

• mention that item type must be Zabbix aggregate
• a screenshot of item configuration page

The idea is coming from: https://www.zabbix.com/forum/zabbix-troubleshooting-and-problems/410354-cant-get-grpsum-on-items_unsupported-to-work

Here's an example screenshot that I think could be useful to have in the documentation ("Zabbix servers" group could be host group):

3 important fields:

• item type
• key
• value type