The example below documents the problems. In short, \definelabel 
suppresses paragraph indent when the label is at the beginning of a 
paragraph and fails to print the label or generate references with 
alternative=inmargin (or inright, or inleft) when in a footnote.

\defineenumeration fails to work in a footnote.


    \setupindenting[yes,small]
    \definelabel   [ID][
    %\defineenumeration[ID][
        text=,
        after=,
        before=,
        headcolor=red,
        alternative=inright,
       ]
    \starttext
    \starttitle[title={Label testing}]
    \startsubject[title={Problems with \tex{definelabel}}]

       This is a test. It is only a test.

       \ID[id1]This paragraph should be indented, with an ID number
         in the margin. When \tex{ID} is placed at the beginning of the
         paragraph, as it is here, the paragraph is not indented.

       This paragraph has a footnote.\footnote{%
           \ID[id2]The ID number is not printed in the margin with
             {\tt alternative=inright}, {\tt alternative=inmargin},
             or {\tt alternative=inleft}. Without any {\tt
             alternative} the ID number is printed where the macro
             appears. The positioning is unsatisfactory using {\tt
             alternative=right}.%
         } The footnote has an ID number which should be printed in the
         right margin.

       This \ID[id3]paragraph has an ID, but it is not at the beginning
         of the paragraph and the paragraph is properly indented. The
         value of the ID number indicates that \tex{ID} in the footnote
         of the previous paragraph incremented the associated counter,
         but the failure of the references (\tex{in} and \tex{at}) to id2
         suggests that there are other problems.

       \dorecurse{3}{
         ID id#1 is \in[id#1] and is on page \at[id#1].\par}

       References for footnotes are generated without \tt{alternative=}.

    \stopsubject
    \startsubject[title={Problems with \tex{defineenumeration}}]

       When \tex{definelabel} is changed to \tex{defineenumeration},
         the example fails to compile. It does not properly handle
         the \tex{ID} in the footnote, complaining of an extra \} or
         forgotten \tex{endgroup}.

    \stopsubject
    \stoptitle
    \stoptext

-- 
Rik