[DDI-SRG] Bug 65 and relationship between LP-PDP-PI

[Wendy Thomas]

The following action notes refer to the solution to clarify the 
relationships between the logicalproduct, physicaldataproduct, and 
physicalinstance. Bug 65 provides some information on this and the goal of 
the original discussion was to 1) understand why we referenced in the 
directions we did originally, 2) clarify links and the complete chain, and 
3) bring this section closer in structure to the rest of the schemas. 
Below is our solution.   wlt


Action:
.	Restructure PhysicalDataProduct (M) to contain a 
PhysicalStructureScheme (M) of individual PhysicalStructure (V). These can 
be of any type (ASCII fixed, Proprietary, Ncube etc etc.)
.	Content of PhysicalStructure is same as current PDP without the 
BaseRecordLayout
.	PhysicalStructureScheme is followed by a LayoutScheme (M) listing 
of BaseRecordLayout substitution items of any type each referencing one 
PhysicalStructure and one PhysicalSegment within that PhysicalStructure 
(see the reference structure in PI CR2)
.	Each BaseRecordLayout has an identifiable ID
.	PhysicalInstance must now reference a BaseRecordLayout 
substitution item (such as a RecordLayout)
.	Link path will go: PI . BaseRecordLayout . PhysicalSegment . 
LogicalRecord
.	DataItem reference to Variable or Ncube needs to be constrained to 
reference only those variables or Ncubes within the LogicalRecord 
specified by the PhysicalRecordSegment. Use this constrained referencing 
technique all the way up the tree to ensure correct containership.
.	Once up to LogicalRecord description the pointer is identifying 
the contents of the LogicalRecord and these variables/Ncubes can come from 
any logical product (need to allow for inclusion of variables from 
multiple waves and key structures for linking between waves)



Wendy L. Thomas                          Phone: +1 612.624.4389
Data Access Core Director		 Fax:   +1 612.626.8375
Minnesota Population Center              Email: wlt at pop.umn.edu
University of Minnesota
50 Willey Hall
225 19th Avenue South
Minneapolis, MN 55455