diff --git a/src/libiso8601/100_types.h b/src/libiso8601/100_types.h
index 618f8f1..43ac859 100644
--- a/src/libiso8601/100_types.h
+++ b/src/libiso8601/100_types.h
@@ -31,6 +31,7 @@ struct iso8601_date {
 
 
 /*! \brief Date (day portion) precision.
+\ingroup parser
 
 This enumeration will record how precisely the date was specified, as well as the format in use. It
 allows the library to determine the earliest and latest dates that could possibly be represented
@@ -60,6 +61,7 @@ enum iso8601_date_prec {
 
 
 /*! \brief Time precision.
+\ingroup parser
 
 This enumeration records how precisely the time was specified as well as its format. The fractional
 format will record whether it was the hour, minute or second that was specified with a fractional
@@ -68,12 +70,19 @@ encountered.
 
 */
 enum iso8601_time_prec {
+    /*! \brief Don't display date. */
     iso8601_prec_none,
+    /*! \brief Display integer part of hour. */
     iso8601_prec_hour,
+    /*! \brief Display hour and integer part of minute. */
     iso8601_prec_min,
+    /*! \brief Display hour, minute and integer part of second. */
     iso8601_prec_sec,
+    /*! \brief Display hour and fractional part of hour. */
     iso8601_prec_hourfrac,
+    /*! \brief Display hour, minute and fractional part of minute. */
     iso8601_prec_minfrac,
+    /*! \brief Display hour, minute, second and nanoseconds. */
     iso8601_prec_secfrac
 }time_prec;