yet another attempt at actual underscore;
enforce scalable fonts for T1 encoding;

--- a/lib/texinputs/isabelle.sty	Sun Feb 09 13:07:23 2014 +0100
+++ b/lib/texinputs/isabelle.sty	Sun Feb 09 16:17:01 2014 +0100
@@ -197,6 +197,12 @@
 \chardef\isacharbackquoteclose=`\`%
 }
 
+\newcommand{\isabellestyleliteralunderscore}{%
+\isabellestyleliteral%
+\def\isacharunderscore{\textunderscore}%
+\def\isacharunderscorekeyword{\textunderscore}%
+}
+
 \newcommand{\isabellestylesl}{%
 \isabellestyleit%
 \def\isastyle{\small\sl}%

--- a/src/Doc/IsarImplementation/document/root.tex	Sun Feb 09 13:07:23 2014 +0100
+++ b/src/Doc/IsarImplementation/document/root.tex	Sun Feb 09 16:17:01 2014 +0100
@@ -1,4 +1,6 @@
 \documentclass[12pt,a4paper,fleqn]{report}
+\usepackage[T1]{fontenc}
+\usepackage{ae}
 \usepackage{latexsym,graphicx}
 \usepackage[refpage]{nomencl}
 \usepackage{iman,extra,isar,proof}

--- a/src/Doc/IsarRef/document/root.tex	Sun Feb 09 13:07:23 2014 +0100
+++ b/src/Doc/IsarRef/document/root.tex	Sun Feb 09 16:17:01 2014 +0100
@@ -1,4 +1,6 @@
 \documentclass[12pt,a4paper,fleqn]{report}
+\usepackage[T1]{fontenc}
+\usepackage{ae}
 \usepackage{amssymb}
 \usepackage{eurosym}
 \usepackage[english]{babel}

--- a/src/Doc/IsarRef/document/style.sty	Sun Feb 09 13:07:23 2014 +0100
+++ b/src/Doc/IsarRef/document/style.sty	Sun Feb 09 16:17:01 2014 +0100
@@ -39,10 +39,10 @@
 
 \parindent 0pt\parskip 0.5ex
 
-\isabellestyle{literal}
+\isabellestyle{literalunderscore}
 
 \newcommand{\isasymdash}{\isatext{\mbox{-}}}
 
 \railtermfont{\isabellestyle{tt}}
-\railnontermfont{\isabellestyle{literal}}
-\railnamefont{\isabellestyle{literal}}
+\railnontermfont{\isabellestyle{literalunderscore}}
+\railnamefont{\isabellestyle{literalunderscore}}

--- a/src/Doc/System/document/root.tex	Sun Feb 09 13:07:23 2014 +0100
+++ b/src/Doc/System/document/root.tex	Sun Feb 09 16:17:01 2014 +0100
@@ -1,4 +1,6 @@
 \documentclass[12pt,a4paper]{report}
+\usepackage[T1]{fontenc}
+\usepackage{ae}
 \usepackage{supertabular}
 \usepackage{graphicx}
 \usepackage{iman,extra,isar,ttbox}