Question on header.table template in fo stylesheets

I noticed something curious in the header.table template in pagesetup.xsl in the fo stylesheets.

The first thing this template does is set the margin-left (or margin-right for right-to-left languages) attribute to 0pt. It doesn't change the other margin.

I noticed because I set the margin in header.content properties to a negative value to get an hanging header (that is, I want part of the header, in this case the page number, in the outside margin). The hanging header works everywhere except on the verso pages in the index because margin-left is reset for the index.

I'm guessing there is a good reason for this, but I'm not sure what it is.

Does anyone know why this is the case?

Thanks,
Dick
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