DER / BER differences?

   We are studying the PKCS # 7 standard and the DER codification
is mentioned several times all along the document. We could not 
get any information about it. All we know is that DER means 
'Distinghished Encoding Rules'

   Could anybody tell us if there is any difference between DER 
and BER ( ASN.1 Basic Encoding Rules ) ? Where can I find more
information about it.

   Thanks in advance

       Jorge Arasanz

P.D. Please answer directly to me as I dont read the pem-dev list
usually.