Unable to expand \in[refX]

Unable to expand \in[refX]

[Fredrik Sjunnesson]

I want keep track of which other sections any given section refers to by
creating lists like

\fromrefA => refX,refY,refZ
\fromrefB => refY,refZ
...

My plan is to achieve this by writing commands like

\ignore{1.2} \appendtovaluelist{fromrefA}{refX}  
\ignore{1.4} \appendtovaluelist{fromrefA}{refY}  
\ignore{1.3} \appendtovaluelist{fromrefA}{refZ}  
\ignore{1.4} \appendtovaluelist{fromrefB}{refY}  
\ignore{1.3} \appendtovaluelist{fromrefB}{refZ}  
...

to a file that is subsequently processed on the following run. Here
references refX, refY and refX refer to sections 1.2, 1.4 and 1.3,
respectively.

The section numbers will be ignored by ConTeXt but by including this
information the lists can be ordered by section number by simply sorting
the file between the calls to texexec.

However, this simple way to get sorted lists turns out to be too tricky
for me. I am simply unable to write the section numbers to the file.

To be more specific I am not able to expand \in[refX] in such a way that
the resulting section number is written to the file.

Any help would be greatly appreciated.

Thanks in advance,
Fredrik