When you loaded events into session with events/load and want to get selections please use events/get:

By time:

svc=events/get&params={"selector":{
					"type":<text>,
					"expr":<text>,
					"timeFrom":<uint>,
					"timeTo":<uint>,
					"detalization":<uint>
				    },
				    ...
		      }

By index:

svc=events/get&params={"selector":[
				    {
					"type":<text>,
					"expr":<text>,
					"indexFrom":<uint>,
					"indexTo":<uint>,
					"detalization":<uint>,
					"filter1":<uint>
				    },
				    ...
		      ]}

Reponse depends on type specified.
Look at events/check_updates response.

To get custom events intervals use expression in "expr":<text> param instead type param.

"selector": [
    {
    "tf": <uint>, /* intersections interval, time from (unix time) */
    "tt": <uint>, /* intersections interval, time to (unix time) */
	"d": {
	    "<type_name>":{
		"<sensor_id>":[
		    { },
		]
	    },
	}
    }, 
]

"selector":{
    "<type_name>":{
	"<sensor_id>":[
	{ },
	]
    },
},
"summary":{
    "<type_name>":{
	"<sensor_id>":{
	    "<summary_param_value>:<uint>",    /* summary, different for different detectors */
	}
}