How to create multiple logical tests in triggers

[bdo]

Hello,

Someone can explain me how logical tests work in trigger expression :

In my mind, when you try to evaluate expression like :
- A and B or C, zabbix evaluates it as : (A and B ) or C
- A or B and C, zabbix evaluates it as : A ou ( B and C )

What I want to test in trigger expression is :
- (A or B ) and C but when using parenthesis, it seems it does not work correctly.

Someone can test and help me please ?
Thanks
Bdo