function  [depth_str]=date_lbl(cdf,var,depth);
%function [date_str,file_str]=date_lbl(cdf,var);
% or
%function  [date_str,file_str]=date_lbl(cdf,var,depth);
%
if nargin==2,
  depth=mcagt(cdf,'east','''sensor_depth(m)''');  % depth of current observation
end
depth_str=['Instrument Depth= ' int2str(depth) ' m'];
