The Interdict isn’t depicted in the series—with a few possible exceptions—if a wizard casts a spell with “incomprehensible words” that might be it. (For some reason it doesn’t seem to apply to sufficiently basic magic spells—most of the magic that’s been retained might fall into this category though.) What follows is thus speculation:
Yes, wizards can invent spells. The Interdict is like a spell that prevents you from reading people’s notes on their new spells, or hearing the words (possibly without their permission). It prevent knowledge transmission (but not generation) via “non-living mediums”. And possibly, unintentional verbal transmission, but not intentional.
The Interdict isn’t depicted in the series—with a few possible exceptions—if a wizard casts a spell with “incomprehensible words” that might be it. (For some reason it doesn’t seem to apply to sufficiently basic magic spells—most of the magic that’s been retained might fall into this category though.) What follows is thus speculation:
Yes, wizards can invent spells. The Interdict is like a spell that prevents you from reading people’s notes on their new spells, or hearing the words (possibly without their permission). It prevent knowledge transmission (but not generation) via “non-living mediums”. And possibly, unintentional verbal transmission, but not intentional.