| Auxiliary information to allow a printing application to use
the channel for data submission to the printer. An application
capable of using a specific PrtChannelType should be able to
use the combined information from the prtChannelInformation and
other channel and interface group objects to 'bootstrap' its
use of the channel. prtChannelInformation is not intended to
provide a general channel description, nor to provide
information that is available once the channel is in use.
The encoding and interpretation of the prtChannelInformation
object is specific to channel type. The description of each
PrtChannelType enum value for which prtChannelInformation is
defined specifies the appropriate encoding and interpretation,
including interaction with other objects. For channel types
that do not specify a prtChannelInformation value, its value
shall be null (0 length).
When a new PrtChannelType enumeration value is registered, its
accompanying description must specify the encoding and
interpretation of the prtChannelInformation value for the
channel type. prtChannelInformation semantics for an existing
PrtChannelType may be added or amended in the same manner as
described in section 2.4.1 for type 2 enumeration values.
The prtChannelInformation specifies values for a collection of
channel attributes, represented as text according to the
following rules:
1. The prtChannelInformation is not affected by localization.
2. The prtChannelInformation is a list of entries representing
the attribute values. Each entry consists of the following
items, in order:
a. A keyword, composed of alphabetic characters (A-Z, a-z)
represented by their NVT ASCII [RFC854] codes, that
identifies a channel attribute,
b. The NVT ASCII code for an Equals Sign (=) (code 61) to
delimit the keyword,
c. A data value encoded using rules specific to the
PrtChannelType to with the prtChannelInformation applies which
must in no case allow an octet with value 10 (the NVT ASCII
Line Feed code),
d. the NVT ASCII code for a Line Feed character (code 10) to
delimit the data value.
No other octets shall be present.
Keywords are case-sensitive. Conventionally, keywords are
capitalized (including each word of a multi-word keyword) and
since they occupy space in the prtChannelInformation, they are
kept short.
3. If a channel attribute has multiple values, it is
represented by multiple entries with the same keyword, each
specifying one value. Otherwise, there shall be at most one
entry for each attribute.
4. By default, entries may appear in any order. If there are
ordering constraints for particular entries, these must be
specified in their definitions.
5. The prtChannelInformation value by default consists of text
represented by NVT ASCII graphics character codes. However,
other representations may be specified:
a. In cases where the prtChannelInformation value contains
information not normally coded in textual form, whatever
symbolic representation is conventionally used for the
information should be used for encoding the
prtChannelInformation value. (For instance, a binary port value
might be represented as a decimal number using NVT ASCII
codes.) Such encoding must be specified in the definition of
the value.
b. The value may contain textual information in a character set
other than NVT ASCII graphics characters. (For instance, an
identifier might consist of ISO 10646 text encoded using the
UTF-8 encoding scheme.) Such a character set and its encoding
must be specified in the definition of the value.
6. For each PrtChannelType for which prtChannelInformation
entries are defined, the descriptive text associated with the
PrtChannelType enumeration value shall specify the following
information for each entry:
Title: Brief description phrase, e.g.: 'Port name',
'Service Name', etc.
Keyword: The keyword value, e.g.: 'Port' or 'Service'
Syntax: The encoding of the entry value if it cannot be
directly represented by NVT ASCII.
Status: 'Mandatory', 'Optional', or 'Conditionally
Mandatory'
Multiplicity: 'Single' or 'Multiple' to indicate whether the
entry may be present multiple times.
Description: Description of the use of the entry, other
information required to complete the definition
(e.g.: ordering constraints, interactions between
entries).
Applications that interpret prtChannelInformation should ignore
unrecognized entries, so they are not affected if new entry
types are added. |
