func Begin()
{
/* Number of lines in flat file containing RecInd & elevations */
	num = 300;
}

func OnLineHeader()
{
	output(LH);
/*
flatfile called "geoph_elev" contains RecInd and elevation (2 columns).
*/
	stream= fopen("geoph_elev","r");
/*
read in each line to get the string tokens[0], tokens[1] for each line
Then convert the string tokens to vector values
While also setting up an indexing scheme in vector p to select the 
proper line in the flat file
*/
	for (i=1; i<=num;i++) {
	  	tokens = getTokenLine(stream);
		if (tokens == Nothing)
		{
			print("Nothing read from geometry file");
		}
		else
		n[i]=strtonum(tokens[0]);
		m[i]=strtonum(tokens[1]);
		index = n[i];
		p[index]=i;
		print("Group Number",n[i],"Elevation",m[i],"Index",p[index],"\n");
	}		
}

func OnTrace()
{
/*
Read a trace find the GI index; use this to find which line to use from 
flat file, i.e. the p[] vector; and then find the line k; finally set
the grpelevation equal to the proper elevation read from the flat file
*/
	jndex = Tr.RecInd;
	if (jndex > 100 && jndex < 401 ) {
	k = p[jndex];
	Tr.GrpElv = m[k];
	}
	output(Tr);
}
 
func End()
{
        fclose(stream);
}