<function>udev_device_get_property_value()</function> and
<function>udev_device_get_sysattr_value()</function> return a
pointer to a constant string of the requested value. On error,
- <constant>NULL</constant> is returned.</para>
+ <constant>NULL</constant> is returned. Attributes that may
+ contain <constant>NUL</constant> bytes should not be retrieved
+ with <function>udev_device_get_sysattr_value()</function>;
+ instead, read them directly from the files within the device's
+ <property>syspath</property>.</para>
<para>On success,
<function>udev_device_set_sysattr_value()</function> returns
an integer greater than, or equal to, <constant>0</constant>.
- On failure, a negative error code is returned.</para>
+ On failure, a negative error code is returned. Values that
+ contain <constant>NUL</constant> bytes should not be set with
+ this function; instead, write them directly to the files within
+ the device's <property>syspath</property>.</para>
<para>On success, <function>udev_device_has_tag()</function>
returns <constant>1</constant> or <constant>0</constant>,