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Model views are stored in t_xrefsystem, with Type = 'PView'. Other columns differ depending on type. Sample below.
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Root nodes:
Namespace = 8
Client = 0
Supplier = 'ModelRoot'
Link = NULL
Description = 'vt=Cust;' for custom, as opposed to built-in (or MDG?), roots; blank for built-in ones.
Views folders:
Namespace = 7
Client = 0
Supplier = the GUID of the parent root node
Link = NULL
Slideshow folders:
Namespace = 7
Client = 0
Supplier = the GUID of the parent views folder
Link = NULL
Description = slideshow details; 'APTime=5;AP=1;' for the default auto-play with five-second delay.
Search folders:
Namespace = 9
Client = 0
Supplier = the GUID of the parent views folder
Link = NULL
Description = 'srchID={search GUID};'.
Favorites folders:
Namespace = 10
Client = appears to be sort order within parent views folder
Supplier = the GUID of the parent views folder
Link = NULL
Package in favorites folder:
Namespace = 3
Client = appears to be sort order within parent views folder
Supplier = the GUID of the parent views folder
Link = package GUID
Description = 'sType=Package;'