User exit for ME21N transaction

Hi all,

Is there any user exit which consists of EKKO structure as CHANGING or TABLES parameter. My requirement is when the user press save while creating STO i have to do some validations and keep the document under hold. For this in EKKO table there is one flag indicator called <b>MEMORY</b> field. this field will be BLANK if the document is to be saved and it will be 'X' if the document is to be kept under HOLD. Please also let me know if any other structre has this field or any other field which indicates HOLD/SAVE status.

Thanks in Advance,

Vinod.