Refer to the Server Reference Manaul page 173:
The purpose of the Document CAL is to provide a mechanism by which licensees can license the use of a single document. To prevent the combination of many data models into a single document, there are restrictions in the documents which can be used with the Document CAL. The Named CAL, the Session CAL and the Usage CAL can however be used to open any functional QlikView document.
Most common data models used in QlikView documents can be used for Document CALs. For instance, proper star schemas and snowflake schemas typically have the field with the highest cardinality in the fact table and the keys in dimensional tables have a lower cardinality. For snowflake schemas, the cardinality decreases further as you move away from the fact table. Documents containing such models typically fulfill the above demands and are well suited for Document CALs.
But documents with multiple logical islands are normally not allowed. Multiple logical islands are only allowed if the additional tables are unconnected and contain only few records or one single column.
Further, the document may not contain any loosely coupled tables.
Finally, the cardinality (number of distinct values) of the key fields must decrease as you move away from the fact table.
Basically “Multiple trivial logical islands” means that you have on or a group of tables that are unconnected with the main data model. QlikView does not allow this. Unless it is unconnected “help tables” with less than 500 records, or with a single column.
Thanks for the link, but exactly this document is the reason why I ask:
Documents with multiple logical islands are normally not allowed. Multiple logical islands are only
allowed, if the additional tables are unconnected and contain only few records or a single column.
"Normally not" and "few records" are far too wish-wash as definitions, don't you think?