Word order of pluperfect subjunctive [duplicate]

Question

Consider this sentence:

Dies ist für meinen Partner, ohne dessen Hilfe ich dieses Buch nie hätte schreiben können. _{(Source: Practising Grammar Workbook, p. 197)}

Why is the word order of this pluperfect subjunctive "hätte schreiben können" and not "schreiben können hätte"?

Is this an exception to the rule that the active part of the verb should go to the end in secondary sentences? If so, why? And how is this construction called in German?

Answer 1

I was always taught T.I.M.: Tense - infinitive - modal. Whenever you have this constellation of three verbs jostling for position at the end of the sentence, where one is a modal (sollen/können etc.), the one that denotes the tense comes first, and the modal goes last. Why this should be is beyond me, and what it is called I don't know. But this is how it works.