When is it valid to use this flag for vertex and/or index buffers? While running with extreme validation D3D debug runtime, it's punching me in the gut for using it while locking both types of buffers. In the only situation where I was assaulted ([smile]) for it's use, I'm also using D3DLOCK_READONLY and D3DLOCK_NOSYSLOCK, on pure system-memory buffers. I tried to do some experimenting by disabling the system memory setting, but there's no change. Is it that the no-dirty flag can not be used simultaneously with these other flags? My primary question is: When is the flag useful? For what purpose is it needed? And is it one of those DirectX behaviors that was included -because they can-, and something that is entirely avoidable (ie, usually done another way)? edit: Further experimenting has shown that removing the other flags (D3DLOCK_READONLY and D3DLOCK_NOSYSLOCK) has no effect (still getting jabbed with errors), while loading into either system memory or video memory with the buffers. So I can't seem to find any valid way to use it. Any information is appreciated!

As far as I know, this flag is only valid when locking texture resources.