Hi, Gizmo, I interpret the Pre-Qualified section of the code that, yes, undermatching filler metals are permitted under specific conditions (with reference to Clause 3.3 and the Tables 2.3 and 2.6).
The second paragraph in 3.3 states that the Matching / Undermatching table [in Clause 3.3 which references Tables 2.3 and 2.6] SHALL be used in conjunction with Table 3.1.
Regards, Sol