On 7/19/2018 07:54, Hans van der Meer wrote:
The macro \completeregister[index] placed in \startbackmatter\startappendices typesets as “I Index”. 
How can I change and format with my custom macro the part “Index”? 
Such as using \mytitle{xyz} instead of Index?

No solution found in the Context Wiki.

dr. Hans van der Meer


Try \placeindex or \placeregister[index] and your own section heading. This is analagous to \completecontent and \placecontent.