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Subject: CCT and UDT Schema Modules
The following is taken from the minutes of the ATG meeting in Waldorf last week.1 CCT & DataType Schema ModulesThe objective is to develop UN/CEFACT CCT and UDT schema modules compliant to CCTS that may be used by all groups developing schemas compliant to the CCTS. Furthermore we should submit these to ISO TC154 for fast track processing and publication as the normative schemas providing XML representation of CCTS constructs, i.e. publication as TS. The group further discussed the status of the different restrictions listed in table 8-2 of the CCTS using the UBL paper on CCT schema module as a baseline for discussions. The language used in table 8-2 is not clear on whether these are mandatory or not. The group reviewed table 8-2 and agreed to implement restrictions as follows:
The group then had a lengthy discussion on the CCT and UDT schema modules. The following was concluded: q The CCT schema module should be defined so that it allow for all components defined in the CCTS. This implies that an xsd:complexType will be defined for each CCT. It also implies that e.g. dateTime has to use xsd:string as its base, because of its conformance to the lexical representation of dateTime in xsd. q The UDT schema module should be defined so that it provides efficient XML representation of the CCTS utilising xsd-features and xsd data types to the extent possible. Such approach also implies that we have to remove the run-time link between the UDT and CCT schema modules. The UDT schemas module should be defined so that it could be used in different environments, not only restricted to UN/CEFACT. If a dateTime representation other then the lexical representation
allowed by xsd is required, a qualified date type of base text must be defined.
If combination of the components of the lexical representation of dateTime is
required (e.g. date, month) then these should also be defined as QDTs.
Discussion based on the UBL briefing paper issued by Tim McGrath raising a number of issues with the UBL and OAG use of CCT schema modules. Issue1: Formal Attribute naming of
SC Group agreed that attributes should reflect the formal dictionary entry name of the supplementary component as specified in CCTS. Although not specifically called out in CCTS, in fact supplementary components follow the pattern of tripartate naming. Issue2: xsd:token vs
xsd:normalizedString xsd:token is more restrictive than xsd:normalizedString in that it does not allow leading and trailing spaces or two or more spaces in sequence. Internally in the UN/EDIFACT database code values are stored with leading spaces, although the spaces are not part of the code value itself. The only justifiable reason for using xsd:normalizedString identified was to provide for human readability. This approach is however considered dangerous as it introduces the possibility of errors in a B2B environment. Group agreed to use xsd:token for codes and identifiers. Following the reasoning above also the SC Language. Local. Identifier should use xsd:token. Issue3: Supplementary component
Format The CCT schema module will include an attribute for each of the SC, including format. However in the UDT schema module the format attribute will not be declared where an appropriate xsd:built-in data type can be used. Issue4: Restrictions on Binary Object for Picture, Sound and
Video The CCT schema module will include an attribute for each of the SC for both primary and secondary representation terms. The UDT schema module will only declare those SCs that are appropriate. UDT:BinaryObject will declare an attribute for each SC UDT:Graphic, UDT:Picture, UDT:Sound and UDT:Video will be declare as independent complex types containing only the required SCs as attributes. Issue5: Patterns for Indicator data
type The CCT schema module will include an attribute for each of the SC, including format. The UDT schema module will declare the indicator as xsd:base=boolean with pattern true and false.
CEFACT intends to finalise their CCT and UDT schema modules within the next two weeks following the above.
Mark
Mark R. Crawford Senior Research
Fellow - LMI XML Lead
W3C Advisory Committee, OASIS, RosettaNet Representative Vice Chair - OASIS UBL TC & Chair Naming and Design Rules Subcommittee Chair - UN/CEFACT XML Syntax Working Group Editor - UN/CEFACT Core Components LMI Government
Consulting
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