diff --git a/pysplits/c00.tex b/pysplits/c00.tex
index 78fbb86..94f191e 100644
--- a/pysplits/c00.tex
+++ b/pysplits/c00.tex
@@ -9,7 +9,7 @@ install_name_tool command to tell libpycpdf.so where to find libcpdf.so.
 
 A 'range' is a list of integers specifying page numbers.
 
-Text arguments and results are in UTF8.
+Text arguments and results are in UTF8. Data is of type bytes.
 
 Any function may raise the exception CPDFError, carrying a string describing
 the error. """