Setting ConTeXt alphabetic subsection counter while sections are numbered numeric

Question

I would like to have my subsections numbered as a, b, c with section numbered as 1, 2, 3. I know I have to set \setuphead[subsection][numbercommand=] with a macro but I don't know how do I reset counters in ConTeXt.

%uncomment when done
%\setuphead[subsection][numbercommand=]
\starttext
\startsection[title={Something}]
    \startsubsection[title={This}]
    Some text
    \stopsubsection
    \startsubsection[title={That}]
    Some text
    \stopsubsection
\stopsection
\stoptext

I'd like to have

1. Something

a. This

some text

b. That

some text

Answer 1

You can change the number format with conversion (use a for lower case characters) and select only the subsection part of the number with sectionsegments.

\setuphead
    [subsection]
    [conversion=a,
     sectionsegments=subsection]

\starttext
\startsection[title={Something}]
    \startsubsection[title={This}]
    Some text
    \stopsubsection
    \startsubsection[title={That}]
    Some text
    \stopsubsection
\stopsection
\stoptext