Contents

Finally, the contents field brings carried values described in previous identifier and length fields. For the most parts, simple types have primitive encodings, while structured ones need constructed encodings.

The following table sumarizes encoding for all biult-in types, shows whether an encoding is primitive (P) or constructed(C) and how the various types are represented in available octets or nested encodings.

Type keyword

P/C

tag

 description of representation
INTEGER

P

2

 two's complement binary, minimal number of octets
REAL

P

9

 various possibilities
NULL

P

5

 no contents octets
BOOLEAN

P

1

 single octet: all zeroes equal FALSE, anything else TRUE
ENUMERATED

P

10

 representing number is encoded as INTEGER
BIT STRING

P

3

 bits of the value, first octet indicates number uf unused bits in the last octet

C

3

 segmented value
OCTET STRING

P

4

 the octets of the value

C

4

 segmented value
Character strings

P

x

 the octets representing characters in appropriate standard, the tag depends on character set

C

x

 segmented value
OBJECT IDENTIFIER

P

6

 packed sequence of numbers representing the arc labels
SET

C

17

 component values, in arbitrary order
SEQUENCE

C

16

 component values, in the definition order
SET OF

C

17

 component values, in arbitrary order
SEQUENCE OF

C

16

 component values, in intended order
CHOICE

P/C

x

 as for type of selected alternative, the same for tag
ANY

P/C

x

 as for type actualy used, the same for tag
Tagged (implicit)

P/C

x

 as for base type
Tagged (explicit)

C

x

 nested encoding of equivalent untagged value
Useful types

P/C

x

 as proprietary useful type is defined