You can change the output from the \in and \at commands with \setupreferencing.3. Februar 2016 um 19:10In the ConTeXt reference manual in section 12.5 Cross references I find the following explanation:
I would like to set (interactive) references as the black triangles pointing forward and backward, as displayed here. Although I tried along the lines in the first example, as mentioned at the end of the text, I could not manage to get these triangles.