replace ASCII by macro call
diff --git a/Doc/ref/ref1.tex b/Doc/ref/ref1.tex
index 0b006ba..30bfcce 100644
--- a/Doc/ref/ref1.tex
+++ b/Doc/ref/ref1.tex
@@ -65,7 +65,7 @@
In lexical definitions (as the example above), two more conventions
are used: Two literal characters separated by three dots mean a choice
-of any single character in the given (inclusive) range of ASCII
+of any single character in the given (inclusive) range of \ASCII{}
characters. A phrase between angular brackets (\verb@<...>@) gives an
informal description of the symbol defined; e.g. this could be used
to describe the notion of `control character' if needed.