Using strings in constraints to randomize data

Hi,

 I am using a constraint that uses a string var to randomize a random variable(data). But xcelium give me an error:

Constraint:

constraint data {
    sel_string inside {"A"} -> data[0] == 1;}

Error:

xmvlog: *E,WOUPYR (): As a temporary implementation restriction, string is not permitted in this context.
 |     sel_string inside {"A"} -> data[0] == 1,

Any suggestions, how to get around this?

Thanks,

Preethi