A modelling book is simply a regular book that is tagged to be filtered out of the report and analysis and plans and apps. The idea is those books should be used to setup modelling widgets (dim editor, TI editor etc.). They are not available in report and analysis as they are created by users with modeller or admin role, and differ (conceptually not technically) from the regular exploration/chart/action buttons functionality present on a regular PAW book. In plans and apps, modeling books are not shown as the concept is that the assets there are for planning activities like "verify actuals", "input expenses", etc. and not something like "run a ti". That is of course debatable.
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Julian
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