In Section 7 of his paper, Terence Parr list 5 factors that define how "entangled" a templating engine is.

The interesting thing about his criteria is that although Perrin's paper sees Template and HTML::Mason in different categories, Terence's criteria sees them as equally entangled!

the criteria

Criteria	HTML::Template	Template	HTML::Mason
the view cannot modify the model either by directly altering model data objects or by invoking methods on the model that cause side-effects.	1	0	0
the view cannot perform computations upon dependent data values For example, the view cannot compute book sale prices as “$price*.90”.	1	0	0
the view cannot compare dependent data values, but can test the properties of data such as presence/absence. Tests like $bloodPressure<120 must be moved to the model and replaced with a test for presence such as $bloodPressureOk!=null	1	0	0
the view cannot make data type assumptions. how the hell is that possible?!	0	0	0
data from the model must not contain display or layout information.	0	0	0
TOTALS	3	0	0

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HTML::Seamstress has no particular policies on any of these. Not surprising. It is not a templating system! It could be grossly entangled or cleanly separated depending on the discipline of the object-oriented software developer.