Notes. The different model stability criteria are denoted by the columns ‘γ_⊞ <  0’, ‘Quartic’ and ‘Hyperbolic’, which specify the number of modes that satisfy Eq. (61a), the quartic linear stability criterion (64) and the hyperbolicity check (see first paragraph of Sect. 2.8), respectively. How many of the mode triads fulfill all model stability criteria is given in the column ‘Stab.’. Similarly, the different model validity criteria are denoted by the columns ‘AE’ and ‘Is.’, which specify the number of modes that satisfy the AE validity criterion (Ψ_AE ≤ 0.1, with Ψ_AE defined by Eq. (83)) and the isolation criterion. The number of mode triads satisfying both validity criteria is given in the column ‘Val.’, whereas the number of mode triads satisfying both the model stability and validity criteria is given in the column ‘Stab. and Val.’. The column ‘Total’ contains the total number of mode triads considered for the different models listed in Table 2.