Connected: An Internet Encyclopedia
3.1. Mapping of the DISPLAY-HINT clause
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3. Mapping of the TEXTUAL-CONVENTION macro
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3.1. Mapping of the DISPLAY-HINT clause
3.1. Mapping of the DISPLAY-HINT clause
The DISPLAY-HINT clause, which need not be present, gives a hint as
to how the value of an instance of an object with the syntax defined
using this textual convention might be displayed. The DISPLAY-HINT
clause may be present if and only if the syntax has an underlying
primitive type of INTEGER or OCTET STRING. (Note, however, that the
semantics defined for a particular syntax can cause the use of
DISPLAY-HINT for that syntax to make no sense, e.g., for Counter32
[2].)
When the syntax has an underlying primitive type of INTEGER, the hint
consists of an integer-format specification, containing two parts.
The first part is a single character suggesting a display format,
either: 'x' for hexadecimal, or 'd' for decimal, or 'o' for octal, or
'b' for binary. The second part is always omitted for 'x', 'o' and
'b', and need not be present for 'd'. If present, the second part
starts with a hyphen and is followed by a decimal number, which
defines the implied decimal point when rendering the value. For
example:
Hundredths ::= TEXTUAL-CONVENTION
DISPLAY-HINT "d-2"
...
SYNTAX INTEGER (0..10000)
suggests that a Hundredths value of 1234 be rendered as "12.34"
When the syntax has an underlying primitive type of OCTET STRING, the
hint consists of one or more octet-format specifications. Each
specification consists of five parts, with each part using and
removing zero or more of the next octets from the value and producing
the next zero or more characters to be displayed. The octets within
the value are processed in order of significance, most significant
first.
The five parts of a octet-format specification are:
- the (optional) repeat indicator; if present, this part is a `*',
and indicates that the current octet of the value is to be used as
the repeat count. The repeat count is an unsigned integer (which
may be zero) which specifies how many times the remainder of this
octet-format specification should be successively applied. If the
repeat indicator is not present, the repeat count is one.
- the octet length: one or more decimal digits specifying the number
of octets of the value to be used and formatted by this octet-
specification. Note that the octet length can be zero. If less
than this number of octets remain in the value, then the lesser
number of octets are used.
- the display format, either: `x' for hexadecimal, `d' for decimal,
`o' for octal, or `a' for ascii. If the octet length part is
greater than one, and the display format part refers to a numeric
format, then network-byte ordering (big-endian encoding) is used
interpreting the octets in the value.
- the (optional) display separator character; if present, this part
is a single character which is produced for display after each
application of this octet-specification; however, this character is
not produced for display if it would be immediately followed by the
display of the repeat terminator character for this octet-
specification. This character can be any character other than a
decimal digit and a `*'.
- the (optional) repeat terminator character, which can be present
only if the display separator character is present and this octet-
specification begins with a repeat indicator; if present, this part
is a single character which is produced after all the zero or more
repeated applications (as given by the repeat count) of this
octet-specification. This character can be any character other
than a decimal digit and a `*'.
Output of a display separator character or a repeat terminator
character is suppressed if it would occur as the last character of
the display.
If the octets of the value are exhausted before all the octet-format
specification have been used, then the excess specifications are
ignored. If additional octets remain in the value after interpreting
all the octet-format specifications, then the last octet-format
specification is re-interpreted to process the additional octets,
until no octets remain in the value.
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Connected: An Internet Encyclopedia
3.1. Mapping of the DISPLAY-HINT clause