Concatinating old value and new value for modified columns.

We have 10 detail rows in detail window. If the user double clicks one particular row then it opens the response window with all the 15 columns. So he can modify any values of 15 columns. Once he finished that then he press ok button. So the response window is automatically closed and the modified column/s value/s displayed on the detail window.
Right now the existing program is doing as
Suppose he double clicks on one row and does some modifications out of 15 columns and press ok button, it automatically closed and modified that particular row.
Let’s say he did modifications on two rows out of 10 rows. The existing program is passing 2 rows { ls_uc_row [1]  , ls_uc_row [2] } to update procedure, the remaining values {{ ls_uc_row [3]  , ls_uc_row [4]…ls_uc_row [10]  }are spaces.
Each row like ls_uc_row [1]  { ls_field[1] + ls_field[2] + …. + ls_field[15] }

I need to do find the old value and new value for modified values as well as description of that particular column out of 15 columns. So each modified row I need to add modified fields as [column_desc(char20)+old_value(char10)+new_value(char10)]. If he modified 4 columns out of 15, I need to add 4 more fields for the particular row like the above format.

Thanks for your advance help.