No import parameter start date and end date in BAPI_TRADINGCONTRACT_CREATE (GTM contract)

Hi.

I create GTM contract with BAPI_TRADINGCONTRACT_CREATE. But i not see parametrs import: start dateand end dateof the contract (sales part and purchase part)

These fieldson the screen:

KOMWBHK-GUEBG and KOMWBHK-GUEEN  (sales part)

KOMWBHD-KDATB_MM and KOMWBHD-KDATE_MM (purchase part)

To recordthese fieldsI need to useEKSTENSIONIN?

thanks in advance

PS

sorry formy english)