Docu update

doc/tex/variable.tex

@@ -5,15 +5,15 @@ one of the following time types must be specified:
 
 \vspace*{3mm}
 \hspace*{8mm}\begin{minipage}{15cm}
-\begin{deflist}{{\large\tt TIME\_CONSTANT \ \ }}
-\item[{\large\tt TIME\_CONSTANT }]  For time constant variables
-\item[{\large\tt TIME\_VARIABLE }]  For time varying variables
+\begin{deflist}{{\large\tt TSTEP\_CONSTANT \ \ }}
+\item[{\large\tt TSTEP\_CONSTANT }]  For time constant variables
+\item[{\large\tt TSTEP\_INSTANT }]  For time varying variables
 \end{deflist}
 \end{minipage}
 \vspace*{3mm}
 
-The default data type is 16 bit for GRIB and 32 bit for all other
-file format types. To change the data type use one of the following 
+The default data type is 16 bit for GRIB and 32 bit for all other file
+format types. To change the data type use one of the following 
 predefined constants:
 
 \vspace*{3mm}

src/cdi.h

@@ -172,20 +172,20 @@ extern "C" {
 
 /* TSTEP types */
 
-#define  TSTEP_CONSTANT           0
-#define  TSTEP_INSTANT            1
-#define  TSTEP_AVG                2
-#define  TSTEP_ACCUM              3
-#define  TSTEP_MAX                4
-#define  TSTEP_MIN                5
-#define  TSTEP_DIFF               6
-#define  TSTEP_RMS                7
-#define  TSTEP_SD                 8
-#define  TSTEP_COV                9
-#define  TSTEP_RATIO             10
-#define  TSTEP_RANGE             11
-#define  TSTEP_INSTANT2          12
-#define  TSTEP_INSTANT3          13
+#define  TSTEP_CONSTANT             0  /* Constant            */
+#define  TSTEP_INSTANT              1  /* Instant             */
+#define  TSTEP_AVG                  2  /* Average             */
+#define  TSTEP_ACCUM                3  /* Accumulation        */
+#define  TSTEP_MAX                  4  /* Maximum             */
+#define  TSTEP_MIN                  5  /* Minimum             */
+#define  TSTEP_DIFF                 6  /* Difference          */
+#define  TSTEP_RMS                  7  /* Root mean square    */
+#define  TSTEP_SD                   8  /* Standard deviation  */
+#define  TSTEP_COV                  9  /* Covariance          */
+#define  TSTEP_RATIO               10  /* Ratio               */
+#define  TSTEP_RANGE               11
+#define  TSTEP_INSTANT2            12
+#define  TSTEP_INSTANT3            13
 
 /* TAXIS types */