lib/texinputs/pdfsetup.sty

slightly more standard data merge: Symtax.merge (K true) avoids equality on abstract type Pretty.T and gracefully accepts overriding, Symtab.join prefers first entry as usual;

%%
%% default hyperref setup (both for pdf and dvi output)
%%

\usepackage{color}
\definecolor{linkcolor}{rgb}{0,0,0.5}
\usepackage[colorlinks=true,linkcolor=linkcolor,citecolor=linkcolor,filecolor=linkcolor,pagecolor=linkcolor,urlcolor=linkcolor]{hyperref}