Source : Free On-Line Dictionary of Computing

Packed Encoding Rules
     
         (PER) {ASN.1} encoding rules for
        producing a compact {transfer syntax} for data structures
        described in {ASN.1}, defined in 1994.
     
        PER provides a much more compact encoding then {BER}.  It
        tries to represents the data units using the minimum number of
        {bits}.  The compactness requires that the decoder knows the
        complete {abstract syntax} of the data structure to be
        decoded, however.
     
        Documents: {ITU-T} X.691, {ISO} 8825-2.
     
        (1998-05-19)