Filters for CDR Export

Hi there. Since there is no manual for the CDR Export page, please share the exact desription for the following filters:
Time start gteq, Time start lteq and Time start lt
I need it for proper callibration of exports (will be created via CDR Exports API)
Thanks in advance

gteq = greater than or equal
lteq= less than or equal to
lt = less than

Thanks a lot!