Datatypes R2 Issue 67

Need to document what the acceptable substitution rules are for datatypes.

This table summarizes the allowable datatype substitutions in designs.

There are two circumstances when one would constrain datatypes:

1. Modelling-time: as part of the HDF, done by committee or affilliate
2. Run time: as part of the on the wire format (uses xsi:type) as a constraint of a datatype as used in the serialized model (mostly: the message type)

Relationship to Conformance

Conformance discusses constraints, this is about specialisation. Constraints may be applied without specialisation. to complete this section and discuss with Conformance.

Run-time dataype substitution

• ANY can be substitutioned as below

Template datatype Substitution

This is an open question. Every allowed substitution is also a valid constraint (in the template sense) on the datatype for which it is a substitution. So the template could make the datatype substitution and implementations for templates would have to render the substitution as a constraint.

• GTS

I've got an R-MIM that has GTS in it (see the ActReference R-MIMs in shared messages) since they reference (are an extract of, a summary of) any random act. This requires run-time subtitution. According to Grahame GTS should not be in the above list, in which case I'd have to change the models to use ANY for effectiveTime and constrain the runtime substitution somehow. I dont really want to do that. Rene spronk 06:45, 14 September 2006 (CDT)

Right. That's an interesting issue. Why does it require run time substitution - what are you thinking this will achieve? And you can't change to ANY

At modelling time I won't know what specilaization of GTS has been used in Acts that I'll be referencing. As such I have to allow for all GTS specializations. The acts I'm referencing are based on various R-MIMs, each may have used a different GTS speclilization at modelling-time. Rene spronk 07:37, 14 September 2006 (CDT)

Modelling time datatype substitution

Note that regards to collections, COLL<X> can be substituted with COLL<Y> where Y is a valid constraint on X. Note also the committees can introduce Mixins (UVL, and NPPD) in the models to any attribute (if thy make sense)

The second table is those proposed by Lloyd, but they have no formal basis in the abstract datatypes:

Todo - can | IVL<TS> substitute for PIVL<T>?

Source	Allowed
ANY	anything (including mixins)
BL	nothing
BN	nothing
ED	ST, UID
ST	UID
CD	CE, CV, CO
CE	CV, CO
CV	CO
CO	nothing
CS	nothing
CR	nothing
SC	ST - R2 proposal: add a demotion to support this.
II	nothing
TEL	nothing
AD	nothing
EN	PN, ON, TN
PN	TN - R2 Proposal for demotion
TN	nothing
ON	TN - R2 Proposal for demotion
QTY	TS, MO, REAL, INT, TS, RTO<QTY, QTY>, PQ
INT	nothing
REAL	INT
RTO	nothing
PQ	nothing. Since substituting REAL is not the same as fixing the value of unit to a unitless measure (unit="1"), this is not a safe thing to do. We advise the use of data type constraints to fix the unit to "1".
PQR	nothing
MO	nothing
TS	nothing
SET<T>	T and substitutions of T. We have asked MnM to clarify the implication of substituting a T for a SET<T> in a model with regards to nullFlavor.
LIST<T>	T and substitutions of T
GLIST<T>	T and substitutions of T
SLIST<T>	T and substitutions of T
BAG<T>	T and substitutions of T
IVL<T>	T and substitutions of T
HIST<T>	HXIT<T>, T and substitutions of T
UVP<T>	T and substitutions of T
NPPD<T>	T and substitutions of T
PIVL<T>	nothing
EIVL<T>	nothing
GTS<T>	SET<PIVL<TS>>, SET<EIVL<TS>>
PPD<T>	?