f4 help in table maintainence generator

hi all,

i have to to give f4 for one field in table maintainence of my custom table.

say i have two fields a, b.  say some value  is entered a and then f4 is pressed on b.then i need to show f4 based on the value entered in a.

i have written the code in process on value request event but i need to have only that particular record that is having the currten line on which f4 is pressed so that i can fetch on the basis of value of a only.

if any one can tell me if there is any structure that holds the current record.

regards

vj