Authority-Check for Sales Document Type

Hi All...

I would like to incorporate Authority-Chack for the field Sales Document Type "TVAK-AURT"...

Can any one give me the sample code or exact code..?

I have written Authority-check for Sales Organization as follows...

authority-check object 'V_VBAK_VKO'

id 'VKORG' field i_sales-vkorg

id 'VTWEG' field '00'

id 'SPART' field '00'

id 'ACTVT' field '03'.

if sy-subrc ne 0.

delete i_sales.

BUT HOW TO WRITE FOR V_VBAK_AAT..??