Compiler error C0218

Message: Case label requires literal or symbolic integer constant

Possible error cause: An attempt is made to use a variable as a CASE label.

Error correction: Use only literals and symbolic integer constants.

Example of the error:

PROGRAM PLC_PRG 
VAR
	i : INT;
	a : INT := 2;
END_VAR

CASE i OF
  1: i := i+1;
  a: i := i+2;
ELSE
  i := i+10;
END_CASE;

--> C0218: Case label requires literal or symbolic integer constant