→In-out variable

also known as VAR_IN_OUT variable; according to →IEC-standard: →variable which is used to supply a value to a →program organization unit and which is additionally used to return a value from the program organization unit

The ST-syntax for input variables is listed under "Declaration of in-out variables in ST".
Information on the declaration of variables in →FBD is listed under "Declaring variables in FBD". Information on the declaration of variables in →LD is listed under "Declaring variables in LD and assigning a variable to contact/coil ".