[XSL] Changing the names used for navigation?

[Stephane Bortzmeyer <bortzmeyer@nic.fr>]

I'm using DocBook XSL stylesheets to produce HTML and I would like to change just a
name used in the navigation (replacing Home by TableOfContents because
it is not the real home page).

I can find nothing in the documentation. Of course, I can edit
common/en.xml but I'm looking for a cleaner solution, some variable I
can add in my stylesheet driver, something like:

<gentext key="nav-home" text="Table Of Contents"/> 

but I cannot find what to add. Reading the source only convinced me
that I'm not a XSL guru yet.