I was always talking about the 3 resistor method of failsafe biasing, not any particular 485 driver IC "special feature".
how was I to know?

None of these application notes mention what I was considering, which is driving the line in the SPACE condition only, so that is why I posted here.
That is not RS485, that is J1708 which limits you to 9600 baud and is not the 485 collision avoidance, but collision detection. If you do not go "master permission" you WILL end up in collision detection reather than collision avoidance. I use both, J1708 because I have to, RS485 because I it is faster and better. A busy J1708 bus is handling so many collisions that it severely hampers throughput. As an example: a process that took 12 minutes using J1708 now is done in 20 seconds using RS485.

The code to handle J1708 is about 10 times the size of a RS485 master.

Erik

Ah, an ancedote:
The J1708 specify that after a collision you apply a random delay before attempting again, this way the 2 colliding units will not try again at the same time. Well 2 units both using the Keil rand() pseudorandom function (which give a fixed "random" sequence) were colliding for hours because they constantly tried at the same time.