diff --git a/Doc/ref/ref2.tex b/Doc/ref/ref2.tex
index 036e57d..e0f1e49 100644
--- a/Doc/ref/ref2.tex
+++ b/Doc/ref/ref2.tex
@@ -185,7 +185,9 @@
 
 \strong{Cross-platform compatibility note:} because of the nature of
 text editors on non-UNIX platforms, it is unwise to use a mixture of
-spaces and tabs for the indentation in a single source file.
+spaces and tabs for the indentation in a single source file.  It
+should also be noted that different platforms may explicitly limit the
+maximum indentation level.
 
 A formfeed character may be present at the start of the line; it will
 be ignored for the indentation calculations above.  Formfeed