diff --git a/cpp/field.hpp b/cpp/field.hpp
index 41e7de7c00c32fd5208a204b0fb72706f21c89bd..518cbfebbf8db6fc8e38a7aff48582f2e1b9a5fb 100644
--- a/cpp/field.hpp
+++ b/cpp/field.hpp
@@ -89,7 +89,7 @@ class field
                 const std::string field_name,
                 const int iteration,
                 const bool read = true);
-        int write_slab(
+        int write_rslab(
                 const std::string fname,
                 const std::string field_name,
                 const int iteration,
diff --git a/cpp/field_io.cpp b/cpp/field_io.cpp
index 3804b16fe51cdda37de61f21a9e78f4381f82cf6..875e1cc61738a0d42a1cfaa0a8f6c72498c94dd7 100644
--- a/cpp/field_io.cpp
+++ b/cpp/field_io.cpp
@@ -345,10 +345,14 @@ int field<rnumber, be, fc>::io(
     return EXIT_SUCCESS;
 }
 
+ /** Writes a slab of a real field to a file. The slab starts at index 0 
+  * and ends at thickness in the lowest dimension (z-direction). 
+  * All other dimensions are kept untouched.
+ */
 template <typename rnumber,
           field_backend be,
           field_components fc>
-int field<rnumber, be, fc>::write_slab(
+int field<rnumber, be, fc>::write_rslab(
         const std::string fname,
         const std::string field_name,
         const int iteration,