Character expressions can be concatenated to each other or to substring notations in any order. The resulting value is a character string composed of the concatenated parts. This concatenated string can then be used in the operand field of a SETC instruction, or as a value for comparison in a logical expression.

You need the concatenation character (a period) to separate the apostrophe that ends one character expression from the apostrophe that begins the next.

&BETA    SETC            'ABCDEF'
&BETA    SETC            'ABC'.'DEF'