Hi,
Accumulate Kernel modifies a second bidirectional parameter ‘accum’.
Who orders the side effect?
For example:
img0 = init..
img1 = init..
XXKernel = vxCreateNode(graph, kernelA)
AccKernel = vxCreateNode(graph, VX_KERNEL_ACCUMULATE);
YYKernel = vxCreateNode(graph, kernelB);
vxSetParameter(YYKerenl, 0, VX_INPUT, img1);
vxSetParameter(AccKernel, 0, VX_INPUT, img0);
vxSetParameter(XXKernel, 0, VX_INPUT, img1);
vxSetParameter(AccKernel, 1, VX_BIDIRECTIONAL, img1);
What value is observed by XXKernel and YYKernel?

The modification is ordered by the first vxSetParameter call.
XXKernel observes an accumulated img1 and YYKernel observes an original img1. 
The modification is ordered by the last vxSetParameter call.
XXKernel and YYKernel observe an original img1. 
The modification is ordered by the vxCreateNode call.
XXKernel observes original img1 and YYKernel observes an accumulated img1. 
undefined … ?
Thanks.