I am trying to construct an index of passages and have run into a curious
problem:

The test file is:
\defineregister[Passage][Passages]
\setupregister[Passage][n=1,%
balance=yes,%
pagestyle=\tfx\em,%
textstyle=\tfx,%
criterium=all,%
interaction={pagenumber},%
]
\setupregister[Passage][indicator=no,distance=0.5em]


\starttext

See \Passage{Simplicius+{\em In de caelo}+483.15--19}483.15--19.
\page
See \Passage{Simplicius+{\em In de caelo}+477.3--4}477.3--4

\page

\placeregister[Passage]

\stoptext

The result is an index that puts 483.15–19 *before* 477.3–4

as in

Simplicius
In de caelo

   483.15–19 1
   477.3–4 2
rather than after. How can I fix this?

Alan