forks for integrated headset -- what's all about?

Hi,

I am looking for a road fork. Sometimes I can see in their descriptions
"use with integrated headsets". As far as I can notice the main
difference is their bigger crown and something like "shelf" (I don't
know to name it) on which lower bearing rests.

Does it mean that using "traditional" fork is not allowed if I have a
frame with integrated headset? What's the main difference between these
types of forks?

I would greatly appreciate your explanations.

thanks,
geos

Forks for use with integrated headsets have a very pronounced
"shoulder" at the steerer tube. These forks can be used with any
headset; integrated headsets require the specific fork.
Stay Cool,
Tom

wrote:
Forks for use with integrated headsets have a very pronounced
"shoulder" at the steerer tube. These forks can be used with any
headset; integrated headsets require the specific fork.

Thanks for reply, Tom. If I understood well it's one way compatibility
ie. forks with the description "for integrated headsets" can actually be
used with any headset, while integrated headsets require these specific
forks, and can be used only with them, right?

Could you explain to me, what is the purpose of this "shoulder"?

Thank you,
geos