GX Developer supports the MELSEC instruction list (IL), MELSEC ladderdiagram (LD) and MELSEC sequential function chart (SFC) languages. You canswitch back and forth between IL and LD at will while you are working. You canprogram your own function blocks (MELSEC QnA/QnAS/System Q series), and a widerange of utilities are available for configuring special function modules forthe MELSEC System Q. And 'configure' is the operative word here - youno longer need to program special function modules, you just configure them.