clarify .msh doc

doc/texinfo/gmsh.texi

@@ -3138,18 +3138,21 @@ the nodes is given in @ref{Node ordering}.
 
 @item @var{number-of-string-tags}
 gives the number of string tags that follow. By default the first
-@var{string-tag} is interpreted as the name of the post-processing view,
-and the second as the name of the interpolation scheme.
+@var{string-tag} is interpreted as the name of the post-processing view.
+@c FIXME and the second as the name of the interpolation scheme.
 
 @item @var{number-of-real-tags}
-gives the number of real number tags that follow.
+gives the number of real number tags that follow. By default the first
+@var{real-tag} is interpreted as a time value associated with the
+dataset.
 
 @item @var{number-of-integer-tags}
 gives the number of integer tags that follow. By default the first
-@var{integer-tag} is interpreted as a time step number, the second as
-the number of field components of the data in the view, the third as the
-number of entities (nodes or elements) in the view, and the fourth as
-the partition index for the view data.
+@var{integer-tag} is interpreted as a time step index (starting at 0),
+the second as the number of field components of the data in the view (1,
+3 or 9), the third as the number of entities (nodes or elements) in the
+view, and the fourth as the partition index for the view data (0 for no
+partition).
 
 @item @var{number-of-nodes-per-elements}
 gives the number of node values for an element in an element-based view.