Relation between snmp trap object and trap itslef

Question

I am new to SNMP, I was looking at some mib files and how traps are defined. Seems like they go like this:

dartTrapObjects        OBJECT IDENTIFIER ::= {dart 2}
dartTraps            OBJECT IDENTIFIER ::= {dart 3}

temp OBJECT-TYPE
    SYNTAX        Integer32
    MAX-ACCESS    read-write
    STATUS        current
    DESCRIPTION
        "Description for an integer"
    ::= {dartTrapObjects 1}

overheat NOTIFICATION-TYPE
    OBJECTS
    {
        temp
    }
    STATUS    current
    DESCRIPTION
        "overheat trap"
    ::= {dartTraps 1}

what is object temp doing here? how is it related to the trap? if the agent sends the trap (overheat) what is the point of variable temp in that scenario?