[Gretl-users] searching for underscores in PDF help documents

Hi all, why can I sometimes search successfully for underscore characters in some of the PDF help documents related to gretl , and sometimes not? Or actually, my hypothesis is that it has to do with how the LaTeX formatting is done at the source. And so the real question is, how can we (as the doc authors) make sure that searching is possible? Example: In the gretl user guide, I enter the search term "eviews_", and I find the URL in footnote 1 on p. 18 (A4 version). Also, in the help for the "gig" addon, searching for "gig_set_dist", I get two hits within the main body. However, the occurrence in the appendix of the same document isn't found. This is a bit unfortunate. thanks sven