Halliday & Matthiessen (2014: 525, 525n):
With propositions, the reported clause is finite.* With proposals, it may be (a) finite or (b) non-finite.
* Except for certain projected ideas, which may take a non-finite form on the model of the Latin ‘accusative + infinitive’, e.g. ||| I understood || them to have accepted ||| he doesn’t consider || you to be serious |||. These shade into attributed intensive relational clauses, e.g. [Attributor:] he [Process:] doesn’t consider [Carrier:] you [Attribute:] serious.