how to restrict Invalid record in 0Material_Text Master Data

Hi,

In R/3 ,during legacy data loading through Excel file , invalid Material code ( with Balnk spaces ) gives error BW data .It comes upto PSA & gives error Invalid material code. Because there is no field in for deletion Flag in Material_ text . How we can stop the material in BW.

Thanks with Regards,

Anand Mehrotra.