COBOL pre-allocates memory for everything in the code at runtime. All variables used are created in the WORKING STORAGE section. Nothing is dynamically created or destroyed in a garbage collection sweep. PIC X is a byte of memory, so PIC X(2816) is a block of memory taking 2816 bytes. By default, "PIC" will use the translation base of the machine, e.g. EBCDIC on a mainframe or ASCII on most anything else. "COMP" data types are a way to pack numeric values into a smaller number of bytes, much like INT and FLOAT. PIC 9 is a numeric data type. PIC 9(4) uses 4 bytes of memory to contain the number. PIC 9(4) COMP-5 in particular is a 32-bit signed float. "OCCURS" is used to create an array. "INDEXED BY" also creates the index to the array at the same time. "REDEFINES" means "uses the same memory space as". Putting it all together: 01 MEMORY-AREA-ONE is simply a block of memory using 2816 bytes. Inside that block of memory, there are two float arrays, one called K01-1 with 37 elements, and the other called K02-1 with 1369 element. To reference a given element in an array, you first assign a value to the index, then you can get what you need from the array. e.g. "MOVE 1 TO KO1-1-X." followed by "ADD K01-1 (KO1-1-X) TO TOTAL." I don't know why you use a REDEFINES for a bunch of floats, unless you needed to dump all of them to an output file for some reason, then it's only 1 line of code, rather than writing the loop logic. (I'm a 2nd-gen coder. The old man taught me this stuff when I was 14. His lab classes when he was in school were "paper-tape in, oscilloscope out" and they programmed in binary. He used to quote "Assembler was a godsend." I'm attending the VS 2010 launch in 15 minutes.) Good luck.