Illegal traps

Could someone explain to me about crown vented traps? Why are these illegal.
Does anyone have a picture of one. Not an illistration as I have them.

Also any narratives on the prescence of:

S traps
Drum traps
crown vented traps
Bell traps


This is pretty good

And this site is nice. It is only termanolagy, but still usefull… Termanolagy? is that a word?? LOL

As my old buddy WD would say… I hope this helps.:wink: