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ITIS Phrase Tables, Draft [issued: 04-11-09]
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7
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This is a draft document of the SAE ATIS committee, subject to change.
When used in general messages there are a number of patterns which are allowed in order to meet user and
data issuer needs. Consult J2540 for a complete discussion of this, including the rules for using tokens to
separate indexes from text. Conceptually two major types of uses are found:
1.
Strings which are mostly free text with the occasional index-phrases inserted as needed
2.
Strings which are mostly sequences of index-phrases with occasional free text inserted as needed
The latter is most common and SHOULD be preferred when data creation implementers have a choice.
Implementers of data reception equipment should be prepared to accept any valid J2540 format.
The ITIS list provides a rich set of useful phrases and as a result is intended to largely reduce the need to
use "free text" in creating the composite phrase. Such text is typically limited to "unusual noun" terms or
unique explanatory phrases, such as that shown in within the brackets of the following: "Rail Service Not
Operating Due to: Herds of [pink] Animals, [watch out slippery spot on road surface] Hazardous materials
spill ". When such text is used, it is recommended that the resulting phrase set remains useful if the
additional free text information is removed, which may occur in some delivery environments.
Observe also that this document provides no recommendation regarding the ordering of such phrases; as a
result syntactically valid messages which produce poorly constructed human language can result. Some
standards users address this in varying degrees of detail, but in general it is a function of the message
creation system and not covered by the various message sets.
Regardless of which format of string content ordering is used, implementers SHALL follow the rules and
process of SAE J2540 to insure that successful encoding and decoding of the data shall occur by any party
using this standard.
In anticipation of making SAE ATIS messages more like those found in the rest of ITS (notably TMDD in
this case), it is recommended that implementers group message content into three distinct areas of
"description of the event," "cause of the event" and “advice regarding what to do” and append all three
areas into a single textual stream when the bearer message does not provide separate areas for each of
these. Further, between the first and second items the phrase "Due to: " should be inserted and between the
last two, the phrase "Advice: " should be inserted. It is anticipated that future revisions of the ATIS
standard will provide three distinct places to insert SAE strings [to be labeled description, cause and
advice] and that the last two will be optional in nature. When mapping message content from another ITS
message which supports this three-part construction to one which does not, the above recommendation
SHOULD be followed.
5.2
Use in RDS systems
In general, the ITIS phrases cannot be used in the existing RDS media; however the vast majority of so-
called RDS systems are not in fact using a SubCarrier transmission media (the point of actual restriction)
but are in fact using the RDS phrases as a convenient interim standard from which to construct textual
descriptions. It is recommended that these users SHOULD revise their systems to use the ITIS phrases (as
well as other ITS message set standards) as conditions allow.
This requires some degree of mapping to take place and ultimately must be decided by the implementers as
best fits local needs. In mapping from the use of RDS phrases to that of ITIS phrases, two general cases
occur.
In the first case, a single RDS message can be mapped to one or more ITIS messages. At times this
mapping is subjective, but as ITIS offers a wider set of expressions this is not overly problematical. An
example would be RDS phrase #324 which is rendered as "Disabled vehicle, Right lane blocked ". An
equivalent message made up of three ITIS components would be [0534,8196,0775] which is rendered as