[texhax] plain TeX: separate items by comma in \write environment

[Rodolfo Medina]

David, Philip:

thanks indeed for your help.  It works in both your examples: I'm attaching
both, David's and Philip's respectively, the first to be processed simply by
`tex' and the second by `xetex'.  Now, what I want is to avoid duplicate
entries: i.e., when two or more identical entries are present, just one be
written down.  Please, how can I achieve that...?

Thanks.....

Rodolfo

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