The ++HOLD statement prevents SMP/E from installing a SYSMOD until some special action is taken. The type of action is indicated by the reason ID or class specified on the ++HOLD statement. A reason ID or class value can contain from 1 to 7 alphanumeric characters. To prevent conflicts between IBM- and user-specified values, there are naming conventions for the three types of HOLD reason IDs (error, system, and user), as well as for HOLD classes.