Conjunto de reglas para formatear en binario datos
descritos en ASN.1.
a set of ASN.1 encoding
rules for formatting data in binary.
http://en.wikipedia.org/wiki/Distinguished_Encoding_Rules
encoding rules that may be
applied to values of types defined using the ASN.1 notation
NOTE. Application of these
encoding rules produces a transfer syntax for such values. It is implicit that
the same rules are also to be used for decoding. The DER is more suitable if
the encoded value is small enough to fit into the available memory and there is
a need to rapidly skip over some nested values. [ISO-8825-1:2002]