You must declare a global SET symbol before you can use it. The assembler assigns an initial value to a global SET symbol at its first point of declaration.

Local SET symbols need not be declared explicitly with LCLA, LCLB, or LCLC statements. The assembler considers any undeclared variable symbol found in the name field of a SETA, SETB, SETC, SETAF, or SETCF statement to be a local SET symbol. It is given the initial value specified in the operand field. If the symbol in the name field is subscripted, it is declared as a subscripted SET symbol.