Bash: Reading a file and assigning variables from file

Shell Programming and Scripting
1

I have a file that has four values on each line and I'd like to give each column a variable name and then use those values in each step of a loop. In bash, I believe you could use a while loop to do this or possibly a cat command, but I am super new to programming and I'm having trouble decoding some of the online bash scripting guides. Thanks very much for your help, it's very much appreciated!

#!/bin/bash

for ((N=0; N<=5; N++))
do
AGE=$N
echo making basegrid "$AGE"Ma

(commands)

rotxyz file.xyz xlat xlon xdel > newfile.xyz
done

# and I'd like to read a data file that looks like this and use the data with my rotxyz program:
AGE xlat xlon xdel
AGE xlat xlon xdel
......

2 
while read A B C D
do
        echo "A is $A"
        echo "B is $B"
        echo "C is $C"
        echo "D is $D"
done < flatfile
3

Thanks very very much again