Tagged cells are emphasized by a small additional frame around the cell in the color of the alphanumerical entry in the cell. A cell is tagged as soon as a single tagged message falls into that cell. Here is an example of tagging

MPI_Allreduce

function in Collective Operations Profile:

Filtering in the Collective Operations Profile works the same way as in any other Chart: only the chosen Collective Operations are shown, the rest are filtered out.