[Typo3-dev] How to check this: start_date < end_date

[Radu Cocieru]

Hi !

Can anyone point me towards some info on how to check if the

start_time < end_time

Both start_time and end_time are configured in TCA as:
"config" => Array (
    "type" => "input",
    "size" => "12",
    "max" => "20",
    "eval" => "datetime,required,datetime",
    "checkbox" => "1",
    "default" => "0"
)

Is there a easy way to add smth like, '> FIELD:start_time',  to the "eval" 
for the end_time ?

Thanks
Radu.