In MkIV register formatting is handled differently.
Like in the legacy version, both page numbers and entry text can be
assigned a style to highlight certain entries.
However, where MkII lets you specify sub-styles that are local to a
register, the current version provides the more generic processors.
A processor is defined globally and can be applied to entries of
different lists.
Also, the separation between pagestyle and textstyle has been
removed, which had been redundant anyways.
Processors follow the pattern of
style alternatives
instead and can be configured through the usual style and color
options.
Finally, “->” replaces the double colon as operator for style
application.
The
wiki page on registers
now has a description of processors with examples.
%% step 1: define a register (no plural in MkIV!)
\defineregister [nickname] [style=\WORD\bold,pagestyle=normal]
%% step 2: define a style processor
\defineprocessor [relevant] [style=bold,color=red]
%% step 2a: works with custom styles, too
\definealternativestyle [neato] [\bfb]
\defineprocessor [weird] [style=neato]
\starttext
\title{List of Known Nicknames}
\placenickname
\page
\page text \nickname{foo}
\page text \nickname{bar}
\page text \nickname{baz}
%% step 3: use in text
\page text \nickname[relevant->]{foo}
\page text \nickname{bar}
\page text \nickname{baz}
\page text \nickname{foo}
\page text \nickname[weird->]{bar}
\page text \nickname{baz}
\page text \nickname{foo}
\page text \nickname{bar}
\page text \nickname[relevant->]{baz}
\stoptext
