The default EEGLAB unit for latency is seconds, so it would be your latency within your entire recording epoch (ex. 0, 40, 80 in your example). Are you trying to import your own custom event codes, or are you trying to export your event code files for additional analysis?

i dont have event channel, i have to create event file in text and upload it

Perfect! You can do this manually through the GUI by going to File>Import Event Info>From MATLAB array or ASCII File and load a simple text file with the events in it. Or you can script it; I'll post my command line down below. 

EEG = pop_importevent( EEG, 'append','no','event','G:\\eventdatafile.txt','fields',{'latency' 'type' 'direction'},'skipline',1,'timeunit',1,'optimalign','off');

Latency will always be the first column of data, and it should be in seconds.

Here is an example event file.