Validation checking in XI side( Proxy to file scnario)

Hi,

Our scnario is Proxy to file.

File is generatd in this way :

HDR............................

DTL...........................

ERH............................

TR2............................

HDR is Header,then Detail then Earning History then trailer.

These values are handeled by database table.

Suppose, HDR(1st value of Header line. HDR identify the Header line) is not coming from ABAP side. At that time XI will reject the total file. How do i use this validation in XI side??

Regards,

Sanghamitra